Aromatic amine compound, and light emitting element, light emitting device, and electronic device using aromatic amine compound

ABSTRACT

An object is to provide an aromatic amine compound with excellent heat resistance. Another object is to provide a light emitting element, a light emitting device, and an electronic device with excellent heat resistance. An aromatic amine compound represented by General Formula (1) is provided. The aromatic amine compound represented by General Formula (1) has a high glass transition point and excellent heat resistance. By using the aromatic amine compound represented by General Formula (1) for a light emitting element, a light emitting device, and an electronic device, a light emitting element, a light emitting device, and an electronic device with excellent heat resistance can be obtained.

TECHNICAL FIELD

The present invention relates to an aromatic amine compound, and a lightemitting element, a light emitting device, and an electronic deviceusing the aromatic amine compound.

BACKGROUND ART

In recent years, a light emitting element using a light emitting organiccompound has been actively researched and developed. A basic structureof this light emitting element is that which is formed by sandwiching alayer containing a light emitting organic compound between a pair ofelectrodes. By applying a voltage to this element, electrons and holesare separately injected from the pair of electrodes into the layercontaining a light emitting organic compound, and current flows. Then,recombination of these carriers (the electrons and holes) causes thelight emitting organic compound to form an excited state and to emitlight when the excited state returns to a ground state. Owing to such amechanism, such a light emitting element is referred to as acurrent-excitation light emitting element.

Note that excited states an organic compound forms can be a singletexcited state or a triplet excited state. Light emission from thesinglet excited state is referred to as fluorescence, and light emissionfrom the triplet excited state is referred to as phosphorescence.

A great advantage of such a light emitting element is that the lightemitting element can be manufactured to be thin and lightweight becausethe light emitting element is formed of an organic thin film with, forexample, a thickness of approximately 0.1 μm. In addition, extremelyhigh response speed is another advantage, because time between carrierinjection and light emission is approximately 1 μsec or less. Thesecharacteristics are considered suitable for a flat panel displayelement.

Such a light emitting element is formed in a film shape. Thus, surfaceemission can be easily obtained by forming a large-area element. Thischaracteristic is hard to be obtained by a point light source typifiedby an incandescent lamp or an LED or a line light source typified by afluorescent lamp. Therefore, the above described light emitting elementalso has a high utility value as a surface light source which isapplicable to lighting or the like.

Such a light emitting element has many material-dependent problems inimproving its element characteristics, and improvement in an elementstructure, development of materials, and the like are conducted toovercome the problems.

As one of the causes of deterioration of the current-excitation lightemitting element, deterioration of a material contained in a layercontaining a light emitting substance formed between a pair ofelectrodes is given. Due to current flow in the layer containing a lightemitting substance in the current-excitation light emitting element, thematerial contained in the layer containing a light emitting substance isrepeatedly subjected to oxidation reaction and reduction reaction. Whena material which is easily decomposed by oxidation reaction andreduction reaction is contained in the layer containing a light emittingsubstance, the material is gradually deteriorated by the repeatedoxidation reaction and reduction reaction and the light emitting elementitself is also deteriorated. Thus, development of an electrochemicallystable substance is demanded.

Reference 1 discloses trisarylaminobenzene as a substance with fewelectrochemical changes (Reference 1: Japanese Patent No. 3419534).However, characteristics such as heat resistance are not sufficient yet,and development of an organic compound with better heat resistance isdemanded.

DISCLOSURE OF INVENTION

In view of the above problems, it is an object of the present inventionto provide an aromatic amine compound with excellent heat resistance.

It is another object to provide a light emitting element, a lightemitting device, and an electronic device with excellent heatresistance.

One aspect of the present invention is an aromatic amine compoundrepresented by General Formula (1).

(where each of Ar¹ to Ar³ represents an aryl group having 6 to 12 carbonatoms or a heteroaromatic group having 4 to 9 carbon atoms; each of R¹to R³ represents an alkyl group having 1 to 4 carbon atoms or an arylgroup having 6 to 25 carbon atoms; each of R¹¹ to R¹³ represents ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an arylgroup having 6 to 25 carbon atoms; and each of R²¹ to R²³ represents ahydrogen atom, a methyl group, or a methoxy group.)

The aromatic amine compound represented by General Formula (1) ispreferably an aromatic amine compound represented by General Formula(2).

(where Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; R¹ represents an alkylgroup having 1 to 4 carbon atoms or an aryl group having 6 to 25 carbonatoms; R¹¹ represents a hydrogen atom, an alkyl group having 1 to 4carbon atoms, or an aryl group having 6 to 25 carbon atoms; and each ofR²¹ to R²³ represents a hydrogen atom, a methyl group, or a methoxygroup.)

The aromatic amine compound represented by General Formula (1) is morepreferably an aromatic amine compound represented by General Formula(3).

(where Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; R¹ represents an alkylgroup having 1 to 4 carbon atoms or an aryl group having 6 to 25 carbonatoms; and R¹¹ represents a hydrogen atom, an alkyl group having 1 to 4carbon atoms, or an aryl group having 6 to 25 carbon atoms.)

An aromatic amine compound represented by Structural Formula (21) ismore preferable.

One aspect of the present invention is an aromatic amine compoundrepresented by General Formula (4).

(where each of Ar¹ and Ar² represents an aryl group having 6 to 12carbon atoms or a heteroaromatic group having 4 to 9 carbon atoms; eachof R¹ and R² represents an alkyl group having 1 to 4 carbon atoms or anaryl group having 6 to 25 carbon atoms; each of R¹¹ and R¹² represents ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an arylgroup having 6 to 25 carbon atoms; and each of R³¹ to R³⁴ represents ahydrogen atom, a methyl group, or a silyl group having a substituent.)

The aromatic amine compound represented by General Formula (4) ispreferably an aromatic amine compound represented by General Formula(5).

(where Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; R¹ represents an alkylgroup having 1 to 4 carbon atoms or an aryl group having 6 to 25 carbonatoms; R¹¹ represents a hydrogen atom, an alkyl group having 1 to 4carbon atoms, or an aryl group having 6 to 25 carbon atoms; and each ofR³¹ to R³⁴ represents a hydrogen atom, a methyl group, or a silyl grouphaving a substituent.)

The aromatic amine compound represented by General Formula (4) ispreferably an aromatic amine compound represented by General Formula(6).

(where Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; R¹ represents an alkylgroup having 1 to 4 carbon atoms or an aryl group having 6 to 25 carbonatoms; and R¹¹ represents a hydrogen atom, an alkyl group having 1 to 4carbon atoms, or an aryl group having 6 to 25 carbon atoms.)

An aromatic amine compound represented by Structural Formula (51) ismore preferable.

One of the present invention is an aromatic amine compound representedby General Formula (7).

(where each of Ar¹ to Ar³ represents an aryl group having 6 to 12 carbonatoms or a heteroaromatic group having 4 to 9 carbon atoms; each of Y¹to Y³ represents an arylene group having 6 to 25 carbon atoms; each ofR¹¹ to R¹⁶ represents a hydrogen atom, an alkyl group having 1 to 4carbon atoms, or an aryl group having 6 to 25 carbon atoms; and each ofR²¹ to R²³ represents a hydrogen atom, a methyl group, or a methoxygroup.)

The aromatic amine compound represented by General Formula (7) ispreferably an aromatic amine compound represented by General Formula(8).

(where Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; Y¹ represents anarylene group having 6 to 25 carbon atoms; each of R¹¹ and R¹²represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms,or an aryl group having 6 to 25 carbon atoms; and each of R²¹ to R²³represents a hydrogen atom, a methyl group, or a methoxy group.)

The aromatic amine compound represented by General Formula (7) is morepreferably an aromatic amine compound represented by General Formula(9).

(where Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; Y¹ represents anarylene group having 6 to 25 carbon atoms; and each of R¹¹ and R¹²represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms,or an aryl group having 6 to 25 carbon atoms.)

An aromatic amine compound represented by Structural Formula (81) ismore preferable.

One aspect of the present invention is an aromatic amine compoundrepresented by General Formula (10).

(where each of Ar¹ and Ar² represents an aryl group having 6 to 12carbon atoms or a heteroaromatic group having 4 to 9 carbon atoms; eachof Y¹ and Y² represents an arylene group having 6 to 25 carbon atoms;each of R¹¹ to R¹⁴ represents a hydrogen atom, an alkyl group having 1to 4 carbon atoms, or an aryl group having 6 to 25 carbon atoms; andeach of R³¹ to R³⁴ represents a hydrogen atom, a methyl group, or asilyl group having a substituent.)

The aromatic amine compound represented by General Formula (10) ispreferably an aromatic amine compound represented by General Formula(11).

(where Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; Y¹ represents anarylene group having 6 to 25 carbon atoms; each of R¹¹ and R¹²represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms,or an aryl group having 6 to 25 carbon atoms; and each of R³¹ to R³⁴represents a hydrogen atom, a methyl group, or a silyl group having asubstituent.)

The aromatic amine compound represented by General Formula (10) ispreferably an aromatic amine compound represented by General Formula(12).

(where Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; Y¹ represents anarylene group having 6 to 25 carbon atoms; and each of R¹¹ and R¹²represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms,or an aryl group having 6 to 25 carbon atoms.)

An aromatic amine compound represented by Structure Formula (111) ismore preferable.

One aspect of the present invention is a light emitting elementincluding a layer containing a light emitting substance between a pairof electrodes, in which the layer containing a light emitting substancecontains the above aromatic amine compound.

Another aspect of the present invention is a light emitting elementincluding a layer containing a light emitting substance between a firstelectrode and a second electrode, in which the layer containing a lightemitting substance includes a light emitting layer and a layercontaining the aromatic amine compound on a side closer to the firstelectrode from the light emitting layer, and the light emittingsubstance emits light when a voltage is applied so that a potential ofthe first electrode becomes higher than that of the second electrode.

Another aspect of the present invention is a light emitting elementincluding a layer containing a light emitting substance between a pairof electrodes, in which the layer containing a light emitting substanceincludes a light emitting layer, and the light emitting layer containsthe above-described aromatic amine compound.

One feature of a light emitting device of the present invention is toinclude a light emitting element in which a layer containing a lightemitting substance is included between a pair of electrodes, in whichthe layer containing a light emitting substance contains theabove-described aromatic amine compound, and a control means ofcontrolling light emission of the light emitting element. Note that thelight emitting device in this specification refers to an image displaydevice, a light emitting device, or a light source (including a lightingsystem). Further, the light emitting device could be any of thefollowing modules: a module having a panel provided with a connectorsuch as an FPC (Flexible Printed Circuit), a TAB (Tape AutomatedBonding) tape, or a TCP (Tape Carrier Package); a module having a TABtape or a TCP provided with a printed wiring board at the end thereof;and a module having an IC (Integrated Circuit) directly mounted on alight emitting element by a COG (Chip On Glass) method.

The present invention also includes in its scope an electronic deviceusing the light emitting element of the present invention for a displayportion. Therefore, one feature of an electronic device of the presentinvention is to include a display portion, in which the display portionhas a control means to control the above-described light emittingelement and light emission of the light emitting element.

The aromatic amine compounds of the present invention have a high glasstransition point and excellent heat resistance.

By using the aromatic amine compound of the present invention for alight emitting element, a light emitting device, and an electronicdevice, a light emitting element, a light emitting device, and anelectronic device with excellent heat resistance can be obtained.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A to 1C are diagrams for explaining a light emitting element ofthe present invention.

FIG. 2 is a diagram for explaining a light emitting element of thepresent invention.

FIGS. 3A and 3B are diagrams for explaining a light emitting device ofthe present invention.

FIG. 4 is a diagram for explaining a light emitting device of thepresent invention.

FIGS. 5A to 5D are diagrams for explaining electronic devices of thepresent invention.

FIG. 6 is a diagram for explaining an electronic device of the presentinvention.

FIGS. 7A and 7B are diagrams showing ¹H NMR charts of3-(N-phenylamino)-9-phenylcarbazole.

FIGS. 8A and 8B are diagrams showing ¹H NMR charts ofN,N′,N″-triphenyl-N,N′,N″-tris(9-phenylcarbazol-3-yl)-benzene-1,3,5-triaminethat is an aromatic amine compound of the present invention.

FIG. 9 is a diagram showing absorption spectra in a toluene solution andof a thin film ofN,N′,N″-triphenyl-N,N′,N″-tris(9-phenylcarbazol-3-yl)-benzene-1,3,5-triaminethat is an aromatic amine compound of the present invention.

FIG. 10 is a diagram showing emission spectra in a toluene solution andof a thin film ofN,N′,N″-triphenyl-N,N′,N″-tris(9-phenylcarbazol-3-yl)-benzene-1,3,5-triaminethat is an aromatic amine compound of the present invention.

FIG. 11 is a diagram showing a DSC chart ofN,N′,N″-triphenyl-N,N′,N″-tris(9-phenylcarbazol-3-yl)-benzene-1,3,5-triaminethat is an aromatic amine compound of the present invention.

FIG. 12 is a diagram showing CV measurement results ofN,N′,N″-triphenyl-N,N′,N″-tris(9-phenylcarbazol-3-yl)-benzene-1,3,5-triamine that is an aromatic aminecompound of the present invention.

FIGS. 13A and 13B are diagrams showing ¹H NMR charts ofN,N′-bis(9-phenylcarbazol-3-yl)-N,N′-diphenyl-benzene-1,3-diamine thatis an aromatic amine compound of the present invention.

FIG. 14 is a diagram showing absorption spectra in a toluene solutionand of a thin film ofN,N′-bis(9-phenylcarbazol-3-yl)-N,N′-diphenyl-benzene-1,3-diamine thatis an aromatic amine compound of the present invention.

FIG. 15 is a diagram showing emission spectra in a toluene solution andof a thin film ofN,N′-bis(9-phenylcarbazol-3-yl)-N,N′,N″-diphenyl-benzene-1,3-diaminethat is an aromatic amine compound of the present invention.

FIG. 16 is a diagram showing a DSC chart ofN,N′,N″-bis(9-phenylcarbazol-3-yl)-N,N′-diphenyl-benzene-1,3-diaminethat is an aromatic amine compound of the present invention.

FIG. 17 is a diagram showing CV measurement results ofN,N′-bis(9-phenylcarbazol-3-yl)-N,N′-diphenyl-benzene-1,3-diamine thatis an aromatic amine compound of the present invention.

FIG. 18 is a diagram showing a current density-luminance characteristicof a light emitting element manufactured in Example 3.

FIG. 19 is a diagram showing a voltage-luminance characteristic of alight emitting element manufactured in Example 3.

FIG. 20 is a diagram showing an emission spectrum of a light emittingelement manufactured in Example 3.

FIG. 21 is a diagram showing a current density-luminance characteristicof a light emitting element manufactured in Example 4.

FIG. 22 is a diagram showing a voltage-luminance characteristic of alight emitting element manufactured in Example 4.

FIG. 23 is a diagram showing an emission spectrum of a light emittingelement manufactured in Example 4.

FIG. 24 is a diagram showing a current density-luminance characteristicof a light emitting element manufactured in Example 5.

FIG. 25 is a diagram showing a voltage-luminance characteristic of alight emitting element manufactured in Example 5.

FIG. 26 is a diagram showing an emission spectrum of a light emittingelement manufactured in Example 5.

FIG. 27 is a diagram showing a current density-luminance characteristicof a light emitting element manufactured in Example 6.

FIG. 28 is a diagram showing a voltage-luminance characteristic of alight emitting element manufactured in Example 6.

FIG. 29 is a diagram showing an emission spectrum of a light emittingelement manufactured in Example 6.

FIG. 30 is a diagram for explaining a light emitting element of thepresent invention.

FIGS. 31A and 31B are diagrams showing ¹H NMR charts of9-[4-(N-phenylamino)phenyl]carbazole.

FIGS. 32A and 32B are diagrams showing ¹H NMR charts of N,N′,N″-triphenyl-N,N′,N″-tris[4-(carbazol-9-yl)phenyl]-benzene-1,3,5-triaminethat is an aromatic amine compound of the present invention.

FIGS. 33A and 33B are diagrams showing ¹H NMR charts ofN,N′-bis[4-(carbazol-9-yl)phenyl]-N,N′-diphenyl-benzene-1,3-diamine thatis an aromatic amine compound of the present invention.

FIGS. 34A and 34B are diagrams showing ¹H NMR charts of9-(4-{N-[4-(9-carbazolyl)phenyl]-N-phenylamino}phenyl)-10-phenylanthracene.

FIGS. 35A and 35B are diagrams showing ¹H NMR charts of9-[4-N-carbazolyl)]phenyl-10-phenylanthracene.

FIG. 36 is a diagram showing a ¹H NMR chart ofN,N′-bis(spiro-9,9′-bifluorene-2-yl)-N,N′-diphenylbenzidine.

FIG. 37 is a diagram showing a DSC chart of1,3,5-tris{N-(4-diphenylaminophenyl)amino}benzene.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments and examples of the present invention will be hereinafterdescribed with reference to the accompanying drawings. However, thepresent invention is not limited to the following explanation. As iseasily known to a person skilled in the art, the mode and the detail ofthe invention can be variously changed without departing from the spiritand the scope of the present invention. Therefore, the present inventionis not interpreted as being limited to the following description of theembodiments and the examples.

Embodiment 1

The present invention is an aromatic amine compound represented byGeneral Formula (1).

(where each of Ar¹ to Ar³ represents an aryl group having 6 to 12 carbonatoms or a heteroaromatic group having 4 to 9 carbon atoms; each of R¹to R³ represents an alkyl group having 1 to 4 carbon atoms or an arylgroup having 6 to 25 carbon atoms; each of R¹¹ to R¹³ represents ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an arylgroup having 6 to 25 carbon atoms; and each of R²¹ to R²³ represents ahydrogen atom, a methyl group, or a methoxy group.)

In General Formula (1), each of Ar¹ to Ar³ represents an aryl grouphaving 6 to 12 carbon atoms or a heteroaromatic group having 4 to 9carbon atoms. Specifically, substituents represented by StructuralFormulas (13-1) to (13-17) are given. Preferably, each of Ar¹ to Ar³ isan aryl group having 6 to 12 carbon atoms.

In General Formula (1), each of R¹ to R³ represents an alkyl grouphaving 1 to 4 carbon atoms or an aryl group having 6 to 25 carbon atoms.Specifically, substituents represented by Structural Formulas (14-1) to(14-16) are given.

In General Formula (1), each of R¹¹ to R¹³ represents a hydrogen atom,an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to25 carbon atoms. Specifically, substituents represented by StructuralFormulas (15-1) to (15-17) are given.

In General Formula (1), Ar¹, Ar², and Ar³ are preferably the samesubstituents.

In General Formula (1), R¹, R², and R³ are preferably the samesubstituents.

In General Formula (1), R¹¹, R¹², and R¹³ are preferably the samesubstituents.

When Ar¹, Ar², and Ar³ are the same substituents, R¹, R², and R³ are thesame substituents, and R¹¹, R¹², and R¹³ are the same substituents,synthesis becomes easier. In other words, by reacting the same threesecondary amines with 1,3,5-trihalogenated benzene, the aromatic aminecompound of the present invention can be obtained.

In other words, an aromatic amine compound represented by GeneralFormula (2) is preferable.

(where Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; R¹ represents an alkylgroup having 1 to 4 carbon atoms or an aryl group having 6 to 25 carbonatoms; R¹¹ represents a hydrogen atom, an alkyl group having 1 to 4carbon atoms, or an aryl group having 6 to 25 carbon atoms; and each ofR²¹ to R²³ represents a hydrogen atom, a methyl group, or a methoxygroup.)

In General Formulas (1) and (2), each of R²¹ to R²³ is preferably ahydrogen atom. When each of R²¹ to R²³ is a hydrogen atom, synthesisbecomes easier.

In other words, an aromatic amine compound represented by GeneralFormula (3) is preferable.

(where Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; R¹ represents an alkylgroup having 1 to 4 carbon atoms or an aryl group having 6 to 25 carbonatoms; and R¹¹ represents a hydrogen atom, an alkyl group having 1 to 4carbon atoms, or an aryl group having 6 to 25 carbon atoms.)

In addition, one aspect of the present invention is an aromatic aminecompound represented by General Formula (4).

(where each of Ar¹ and Ar² represents an aryl group having 6 to 12carbon atoms or a heteroaromatic group having 4 to 9 carbon atoms; eachof R¹ and R² represents an alkyl group having 1 to 4 carbon atoms or anaryl group having 6 to 25 carbon atoms; each of R¹¹ and R¹² represents ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an arylgroup having 6 to 25 carbon atoms; and each of R³¹ to R³⁴ represents ahydrogen atom, a methyl group, or a silyl group having a substituent.)

In General Formula (4), each of Ar¹ and Ar² represents an aryl grouphaving 6 to 12 carbon atoms or a heteroaromatic group having 4 to 9carbon atoms. Specifically, the substituents represented by StructuralFormulas (13-1) to (13-17) are given. Preferably, each of Ar¹ and Ar² isan aryl group having 6 to 12 carbon atoms.

In General Formula (4), each of R¹ and R² represents an alkyl grouphaving 1 to 4 carbon atoms or an aryl group having 6 to 25 carbon atoms.Specifically, the substituents represented by Structural Formulas (14-1)to (14-16) are given.

In General Formula (4), each of R¹¹ and R¹² represents a hydrogen atom,an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to25 carbon atoms. Specifically, the substituents represented byStructural Formulas (15-1) to (15-17) are given.

In General Formula (4), Ar¹ and Ar² are preferably the samesubstituents.

In General Formula (4), R¹ and R² are preferably the same substituents.

In General Formula (4), R¹¹ and R¹² are preferably the samesubstituents.

When Ar¹ and Ar² are the same substituents, R¹ and R² are the samesubstituents, and R¹¹ and R¹² are the same substituents, synthesisbecomes easier. In other words, by reacting the same two secondaryamines with 1,3-dihalogenated benzene, the aromatic amine compound ofthe present invention can be obtained.

In other words, an aromatic amine compound represented by GeneralFormula (5) is preferable.

(where Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; R¹ represents an alkylgroup having 1 to 4 carbon atoms or an aryl group having 6 to 25 carbonatoms; R¹¹ represents a hydrogen atom, an alkyl group having 1 to 4carbon atoms, or an aryl group having 6 to 25 carbon atoms; and each ofR³¹ to R³⁴ represents a hydrogen atom, a methyl group, or a silyl grouphaving a substituent.)

In General Formulas (4) and (5), each of R³¹ to R³⁴ is preferably ahydrogen atom. When each of R³¹ to R³⁴ is a hydrogen atom, synthesisbecomes easier.

In other words, an aromatic amine compound represented by GeneralFormula (6) is preferable.

(where Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; R¹ represents an alkylgroup having 1 to 4 carbon atoms or an aryl group having 6 to 25 carbonatoms; and R¹¹ represents a hydrogen atom, an alkyl group having 1 to 4carbon atoms, or an aryl group having 6 to 25 carbon atoms.)

In addition, one aspect of the present invention is an aromatic aminecompound represented by General Formula (7).

(where each of Ar¹ to Ar³ represents an aryl group having 6 to 12 carbonatoms or a heteroaromatic group having 4 to 9 carbon atoms; each of Y¹to Y³ represents an arylene group having 6 to 25 carbon atoms; each ofR¹¹ to R¹⁶ represents a hydrogen atom, an alkyl group having 1 to 4carbon atoms, or an aryl group having 6 to 25 carbon atoms; and each ofR²¹ to R²³ represents a hydrogen atom, a methyl group, or a methoxygroup.)

In General Formula (7), each of Ar¹ to Ar³ represents an aryl grouphaving 6 to 12 carbon atoms or a heteroaromatic group having 4 to 9carbon atoms. Specifically, substituents represented by StructuralFormulas (16-1) to (16-17) are given. Preferably, each of Ar¹ to Ar³ isan aryl group having 6 to 12 carbon atoms.

In General Formula (7), each of Y¹ to Y³ represents an arylene grouphaving 6 to 25 carbon atoms. Specifically, substituents represented byStructural Formulas (17-1) to (17-7) are given.

In General Formula (7), each of R¹¹ to R¹⁶ represents a hydrogen atom,an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to25 carbon atoms. Specifically, substituents represented by StructuralFormulas (18-1) to (18-17) are given.

In General Formula (7), Ar¹, Ar², and Ar³ are preferably the samesubstituents.

In General Formula (7), Y¹, Y² and Y³ are preferably the samesubstituents.

In General Formula (7), R¹¹, R¹³, and R¹⁵ are preferably the samesubstituents.

In General Formula (7), R¹², R¹⁴, and R¹⁶ are preferably the samesubstituents.

When Ar¹, Ar², and Ar³ are the same substituents, Y¹, Y² and Y³ are thesame substituents, R¹¹, R¹³, and R¹⁵ are the same substituents, and R¹²,R¹⁴, and R¹⁶ are the same substituents, synthesis becomes easier. Inother words, by reacting the same three secondary amines with1,3,5-trihalogenated benzene, the aromatic amine compound of the presentinvention can be obtained.

In other words, an aromatic amine compound represented by GeneralFormula (8) is preferable.

(where Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; Y¹ represents anarylene group having 6 to 25 carbon atoms; each of R¹¹ and R¹²represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms,or an aryl group having 6 to 25 carbon atoms; and each of R²¹ to R²³represents a hydrogen atom, a methyl group, or a methoxy group.)

In General Formulas (7) and (8), each of R²¹ to R²³ is preferably ahydrogen atom. When each of R²¹ to R²³ is a hydrogen atom, synthesisbecomes easier.

In other words, an aromatic amine compound represented by GeneralFormula (9) is preferable.

(where Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; Y¹ represents anarylene group having 6 to 25 carbon atoms; and each of R¹¹ and R¹²represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms,or an aryl group having 6 to 25 carbon atoms.)

In addition, one aspect of the present invention is an aromatic aminecompound represented by General Formula (10).

(where each of Ar¹ and Ar² represents an aryl group having 6 to 12carbon atoms or a heteroaromatic group having 4 to 9 carbon atoms; eachof Y¹ and Y² represents an arylene group having 6 to 25 carbon atoms;each of R¹¹ to R¹⁴ represents a hydrogen atom, an alkyl group having 1to 4 carbon atoms, or an aryl group having 6 to 25 carbon atoms; andeach of R³¹ to R³⁴ represents a hydrogen atom, a methyl group, or asilyl group having a substituent.)

In General Formula (10), each of Ar¹ and Ar² represents an aryl grouphaving 6 to 12 carbon atoms or a heteroaromatic group having 4 to 9carbon atoms. Specifically, the substituents represented by StructuralFormulas (16-1) to (16-17) are given. Preferably, each of Ar¹ to Ar³ isan aryl group having 6 to 12 carbon atoms.

In General Formula (10), each of Y¹ and Y² represents an arylene grouphaving 6 to 25 carbon atoms. Specifically, the substituents representedby Structural Formulas (17-1) to (17-7) are given.

In General Formula (10), each of R¹¹ to R¹⁴ represents a hydrogen atom,an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to25 carbon atoms. Specifically, the substituents represented byStructural Formulas (18-1) to (18-17) are given.

In General Formula (10), Ar¹ and Ar² are preferably the samesubstituents.

In General Formula (10), Y¹ and Y² are preferably the same substituents.

In General Formula (10), R¹¹ and R¹³ are preferably the samesubstituents.

In General Formula (10), R¹² and R¹⁴ are preferably the samesubstituents.

When Ar¹ and Ar² are the same substituents, Y¹ and Y² are the samesubstituents, R¹¹ and R¹³ are the same substituents, and R¹² and R¹⁴ arethe same substituents, synthesis becomes easier. In other words, byreacting the same two secondary amines with 1,3-dihalogenated benzene,the aromatic amine compound of the present invention can be obtained.

In other words, an aromatic amine compound represented by GeneralFormula (11) is preferable.

(where Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; Y¹ represents anarylene group having 6 to 25 carbon atoms; each of R¹¹ and R¹²represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms,or an aryl group having 6 to 25 carbon atoms; and each of R³¹ to R³⁴represents a hydrogen atom, a methyl group, or a silyl group having asubstituent.)

In General Formulas (10) and (11), each of R³¹ to R³⁴ is preferably ahydrogen atom. When each of R³¹ to R³⁴ is a hydrogen atom, synthesisbecomes easier.

In other words, an aromatic amine compound represented by GeneralFormula (12) is preferable.

(where Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; Y¹ represents anarylene group having 6 to 25 carbon atoms; and each of R¹¹ and R¹²represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms,or an aryl group having 6 to 25 carbon atoms.)

As specific examples of the aromatic amine compound of the presentinvention, aromatic amine compounds represented by Structural Formulas(21) to (142) are given. However, the present invention is not limitedto these.

The aromatic amine compound of the present invention represented by thefollowing General Formula (1) can be synthesized by a synthesis methodshown in Synthetic Schemes (A-1) and (A-2). First, a compound includingcarbazole in a skeleton (Compound A) is reacted with halogen or halidesuch as N-bromosuccinimide (NBS), N-iodosuccinimide (NIS), bromine(Br₂), potassium iodide (KI), or iodine (I₂) to synthesize a compoundincluding 3-bromocarbazole in a skeleton (Compound B), and thensubjected to coupling reaction with a primary amine using a metalcatalyst such as a palladium catalyst (Pd catalyst), thereby obtainingCompound C. By reacting obtained Compound C with 1,3,5-trihalogenatedbenzene using a metal catalyst such as a Pd catalyst, an aromatic aminecompound of the present invention can be obtained.

In General Formula (1) and Synthetic Schemes (A-1) and (A-2), each ofAr¹ to Ar³ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; each of R¹ to R³represents an alkyl group having 1 to 4 carbon atoms or an aryl grouphaving 6 to 25 carbon atoms; each of R¹¹ to R¹³ represents a hydrogenatom, an alkyl group having 1 to 4 carbon atoms, or an aryl group having6 to 25 carbon atoms; and each of R²¹ to R²³ represents a hydrogen atom,a methyl group, or a methoxy group.

Note that in Synthetic Scheme (A-2), the aromatic amine compound of thepresent invention in General Formula (2) can be obtained throughone-stage reaction by reacting 3 equivalents of one kind of Compound Cwith 1 equivalent of 1,3,5-trihalogenated benzene. In other words, thearomatic amine compound of the present invention in General Formula (2)is characterized by easy synthesis.

In addition, an aromatic amine compound of the present inventionrepresented by the following General Formula (4) can be synthesized by asynthesis method shown in the above Synthetic Scheme (A-1) and thefollowing Synthetic Scheme (A-3). The aromatic amine compound of thepresent invention can be obtained by reacting Compound C obtainedaccording to Synthetic Scheme (A-1) with 1,3-dihalogenated benzene usinga metal catalyst such as a Pd catalyst.

In General Formula (4) and Synthetic Scheme (A-3), each of Ar¹ and Ar²represents an aryl group having 6 to 12 carbon atoms or a heteroaromaticgroup having 4 to 9 carbon atoms; each of R¹ and R² represents an alkylgroup having 1 to 4 carbon atoms or an aryl group having 6 to 25 carbonatoms; each of R¹¹ and R¹² represents a hydrogen atom, an alkyl grouphaving 1 to 4 carbon atoms, or an aryl group having 6 to 25 carbonatoms; and each of R³¹ to R³⁴ represents a hydrogen atom, a methylgroup, or a silyl group having a substituent.

Note that in Synthetic Scheme (A-3), the aromatic amine compound of thepresent invention in General Formula (5) can be obtained throughone-stage reaction by reacting 2 equivalents of one kind of Compound Cwith one equivalent of 1,3-dihalogenated benzene. In other words, thearomatic amine compound of the present invention in General Formula (5)is characterized by easy synthesis.

An aromatic amine compound of the present invention represented by thefollowing General Formula (7) can be synthesized by synthesis methodshown in Synthetic Scheme (A-4) and Synthetic Scheme (A-5). First, acompound including carbazole in a skeleton (Compound D) is reacted withdihalogenated aryl to synthesize a compound including N-halogenatedarylcarbazole (Compound E), and then subjected to coupling reaction witha secondary amine using a metal catalyst such as copper iodide (CuI),thereby obtaining Compound E By reacting Compound F obtained with1,3,5-trihalogenated benzene using a Pd catalyst, the aromatic aminecompound of the present invention can be obtained.

In General Formula (7) and Synthetic Schemes (A-4) and (A-5), each ofAr¹ to Ar³ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; each of Y¹ to Y³represents an arylene group having 6 to 25 carbon atoms; each of R¹¹ toR¹⁶ represents a hydrogen atom, an alkyl group having 1 to 4 carbonatoms, or an aryl group having 6 to 25 carbon atoms; and each of R²¹ toR²³ represents a hydrogen atom, a methyl group, or a methoxy group.

Note that in Synthetic Scheme (A-5), the aromatic amine compound of thepresent invention in General Formula (8) can be obtained throughone-stage reaction by reacting 3 equivalents of one kind of Compound Ewith one equivalent of 1,3,5-trihalogenated benzene. In other words, thearomatic amine compound of the present invention in General Formula (8)is characterized by easy synthesis.

In addition, an aromatic amine compound of the present inventionrepresented by the following General Formula (10) can be synthesized bysynthesis methods shown in the above Synthetic Scheme (A-4) and thefollowing Synthetic Scheme (A-6). The aromatic amine compound of thepresent invention can be obtained by reacting Compound F obtainedaccording to Synthetic Scheme (A-4) with 1,3-dihalogenated benzene usinga metal catalyst such as a Pd catalyst.

In General Formula (10) and Synthetic Scheme (A-6), Ar¹ represents anaryl group having 6 to 12 carbon atoms or a heteroaromatic group having4 to 9 carbon atoms; Y¹ represents an arylene group having 6 to 25carbon atoms; each of R¹¹ and R¹² represents a hydrogen atom, an alkylgroup having 1 to 4 carbon atoms, or an aryl group having 6 to 25 carbonatoms; and each of R²¹ to R²³ represents a hydrogen atom, a methylgroup, or a methoxy group.

Note that in Synthetic Scheme (A-6), the aromatic amine compound of thepresent invention in General Formula (11) can be obtained throughone-stage reaction by reacting 2 equivalents of one kind of Compound Ewith one equivalent of 1,3-dihalogenated benzene. In other words, thearomatic amine compound of the present invention in General Formula (11)is characterized by easy synthesis.

In the above-described synthetic scheme, a Pd catalyst havingtri(tert-butyl)phosphine(tert-Bu)₃P as a ligand can be used for thecoupling reaction using a metal catalyst. For example, as the Pdcatalyst, a catalyst in which (tert-Bu)₃P is coordinated in Pd by mixingPd(dba)₂ and (tert-Bu)₃P can be used. Note that in place of Pd(dba)₂, aPd complex in which a ligand having weaker coordination strength than(tert-Bu)₃P is coordinated may be used. Specifically, Pd(dba)₂,palladium diacetate (Pd(OAc)₂), or the like can be used. Preferably,Pd(dba)₂ is used. As the ligand, DPPF can be used in place of(tert-Bu)₃P. A reaction temperature is preferably in the range of a roomtemperature to 130° C. When heated to 130° C. or more, the Pd catalystmay be decomposed and may lose a function as a catalyst. It is morepreferable to set a heating temperature in the range of 60° C. to 110°C. because it becomes easier to control the reaction and a yield isincreased. Note that dba refers to trans,trans-dibenzylideneacetone. Inaddition, DPPF refers to 1,1-bis(diphenylphosphino)ferrocene. As asolvent, anhydrous toluene, xylene, or the like can be used. As a base,alkali metal alkoxide such as tert-BuONa can be used.

The aromatic amine compound of the present invention has an excellenthole transporting property. Therefore, a favorable electriccharacteristic can be obtained by using the aromatic amine compound ofthe present invention for an electronics device such as a light emittingelement or a solar cell.

In addition, the aromatic amine compound of the present invention has ahigh glass transition point because it has a carbazole skeleton. Inother words, since the aromatic amine compound of the present inventionhas excellent heat resistance, an electronics device having excellentheat resistance can be obtained by using it for an electronics devicesuch as a light emitting element or a solar cell.

In addition, the aromatic amine compound of the present invention isstable even when oxidation reaction and subsequent reduction reactionare repeated. In other words, the aromatic amine compound of the presentinvention has stability in repetitive oxidation reaction. Therefore, along-life electronics device can be obtained by using the aromatic aminecompound of the present invention for an electronics device such as alight emitting element or a solar cell.

Embodiment 2

One mode of a light emitting element using the aromatic amine compoundof the present invention is hereinafter explained with reference to FIG.1A.

A light emitting element of the present invention has a plurality oflayers between a pair of electrodes. The plurality of layers is alaminate of a combination of layers formed of a material having anexcellent carrier injection property and a material having a highcarrier transport property such that a light emitting region is formedapart from the electrodes, in other words, such that carriers arerecombined in a portion apart from the electrodes.

In this embodiment, the light emitting element includes a firstelectrode 102, a first layer 103, a second layer 104, a third layer 105,and a fourth layer 106 which are sequentially stacked over the firstelectrode 102, and a second electrode 107 which is provided thereover.Note that in this embodiment, explanation is made below assuming thatthe first electrode 102 functions as an anode and the second electrode107 functions as a cathode.

A substrate 101 is used as a support of the light emitting element. Forthe substrate 101, glass, plastic, or the like can be used, for example.Note that another material may be used as long as it functions as asupport in a manufacturing process of the light emitting element.

For the first electrode 102, a metal, an alloy, a conductive compound, amixture of them, or the like having a high work function (specifically,4.0 eV or more) is preferably used. Specifically, indium tin oxide(ITO), indium tin oxide containing silicon, indium zinc oxide (IZO) inwhich indium oxide is mixed with zinc oxide (ZnO) of 2 wt % to 20 wt %,indium oxide containing tungsten oxide of 0.5 wt % to 5 wt % and zincoxide of 0.1 wt % to 1 wt % (IWZO), or the like can be given as anexample. Although these conductive metal oxide films are generallyformed by sputtering, they may be formed by applying a sol-gel method orthe like. In addition, gold (Au), platinum (Pt), nickel (Ni), tungsten(W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper(Cu), palladium (Pd), nitride of a metal material (such as titaniumnitride (TiN)), or the like can be used.

The first layer 103 is a layer containing a substance having anexcellent hole injection property. Molybdenum oxide (MoO_(X)), vanadiumoxide (VO_(X)), ruthenium oxide (RuO_(X)), tungsten oxide (WO_(X)),manganese oxide (MnO_(X)), or the like can be used. Alternatively, thefirst layer 103 can be formed of phthalocyanine-based compound such asphthalocyanine (abbr.: H₂Pc) or copper phthalocyanine (CuPc), a highmolecular compound such as poly(ethylenedioxythiophene)/poly(styrenesulfonic acid) (PEDOT/PSS), or the like.

Alternatively, a composite material formed by combining an organiccompound and an inorganic compound may be used for the first layer 103.In particular, a composite material containing an organic compound andan inorganic compound having an electron accepting property with respectto the organic compound has excellent hole injection and hole transportproperties because the inorganic compound accepts electrons from theorganic compound and carrier density is increased. In this case, theorganic compound is preferably a material having an excellent holetransport property. Specifically, an arylamine compound or a carbazolederivative can be used. Alternatively, aromatic hydrocarbon may be usedas the organic compound. The inorganic compound may be any substance aslong as it has an electron accepting property with respect to theorganic compound, and specifically, oxide of transition metal ispreferable. For example, metal oxide such as titanium oxide (TiO_(X)),vanadium oxide (VO_(X)), molybdenum oxide (MoO_(X)), tungsten oxide(WO_(X)), rhenium oxide (ReO_(X)), a ruthenium oxide (RuO_(X)), chromiumoxide (CrO_(X)), zirconium oxide (ZrO_(X)), hafnium oxide (HfO_(X)),tantalum oxide (TaO_(X)), silver oxide (AgO_(X)), or manganese oxide(MnO_(X)) can be used. In the case of using the composite materialformed by combining an organic compound and an inorganic compound forthe first layer 103, the first layer 103 can form an ohmic contact withthe first electrode 102. Therefore, a material for forming the firstelectrode can be selected regardless of a work function.

The second layer 104 is a layer containing a substance having anexcellent hole transport property. Since the aromatic amine compound ofthe present invention described in Embodiment 1 has an excellent holetransport property, it can be suitably used for the second layer 104. Byusing the aromatic amine compound of the present invention for thesecond layer 104, a light emitting element with favorablecharacteristics can be obtained. In particular, a light emitting elementwith excellent heat resistance can be obtained.

The third layer 105 is layer containing a light emitting substance. Asfor the light emitting substance, various substances can be used withoutparticular limitation, and a coumarin derivative such as coumarin 6 orcoumarin 545T, a quinacridon derivative such as N,N′-dimethylquinacridonor N,N′-diphenylquinacridon, an acridone derivative such asN-phenylacridonoe or N-methylacridone, a condensed aromatic compoundsuch as 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbr.: t-BuDNA),9,10-diphenylanthracene, rubrene, periflanthene, or2,5,8,11-tetra(tert-butyl)perylene (abbr.: TPB), a pyran derivative suchas 4-dicyanomethylene-2-[p-(dimethylamino)styryl]-6-methyl-4H-pyran, anamine derivative such as 4-(2,2-diphenylvinyl)triphenylamine, or thelike can be used. As a phosphorescent light emitting substance, aniridium complex such asbis{2-(p-tolyl)pyridinato}iridium(III)acetylacetonate, bis{2-(2′-benzothienyl)pyridinato}iridium(III)acetylacetonate, orbis{2-(4,6-difluorophenyl)pyridinato}iridium(III)picolinate; a platinumcomplex such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin-platinumcomplex; a rare-earth complex such as 4,7-diphenyl-1,10-phenanthrolinetris(2-thenoyltrifluoroacetonato)europium(III), or the like can be used.

Alternatively, the third layer 105 may be formed by dispersing a lightemitting substance into another substance. As a material into which alight emitting substance is dispersed, various materials can be used.Specifically, a substance having a higher LUMO level and a lower HOMOlevel than a light emitting substance can be used. In addition, pluralkinds of materials can be used as the material into which a lightemitting substance is dispersed. For example, a substance whichsuppresses crystallization of rubrene or the like may further be addedto suppress crystallization. Moreover,4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB),tris(8-quinolinolato)aluminum (Alq), or the like may further be added toefficiently transfer energy to the light emitting substance.

The fourth layer 106 is a layer formed of a substance having anexcellent electron transport property, for example, a metal complexhaving a quinoline skeleton or a benzoquinoline skeleton such astris(8-quinolinolato)aluminum (abbr.: Alq),tris(5-methyl-8-quinolinolato)aluminum (abbr.: Almq₃),bis(10-hydroxybenzo[h]quinolinato)beryllium (abbr.: BeBq₂), orbis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum (abbr.: BAlq),or the like. Alternatively, a metal complex having an oxazole-based orthiazole-based ligand such as bis[2-(2-hydroxyphenyl)benzoxazolato]zinc(abbr.: Zn(BOX)₂) or bis[2-(2-hydroxyphenyl)benzothiazolato]zinc (abbr.:Zn(BTZ)₂), or the like can be used. Furthermore, besides the metalcomplex, 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole(abbr.: PBD),1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene (abbr.:OXD-7), 3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triazole(abbr.: TAZ),3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole(abbr.: p-EtTAZ), bathophenanthroline (abbr.: BPhen), bathocuproin(abbr.: BCP), or the like can be used. The substances described here aremainly substances having electron mobility of 10⁻⁶ cm²/Vs or more. Notethat a substance other than those described above may be used for thefourth layer 106 as long as the substance has a more excellent electrontransport property than hole transport property. In addition, the fourthlayer 106 may be not only a single layer but also stacked layers of twoor more layers formed of the above substance.

As a substance for forming the second electrode 107, a metal, an alloy,a conductive compound, a mixture thereof, or the like having a low workfunction (specifically, 3.8 eV or less) can be used. As a specificexample of such a cathode material, an element belonging to Group 1 or 2of the Periodic Table, in other words, an alkali metal such as lithium(Li) or cesium (Cs), an alkaline earth metal such as magnesium (Mg),calcium (Ca), or strontium (Sr) or an alloy containing these (MgAg,AlLi), a rare earth metal such as europium (Eu) or ytterbium (Yb) or analloy containing these, or the like can be given. However, by providinga layer having a function of promoting electron injection between thesecond electrode 107 and the fourth layer 106 so as to be stacked withthe second electrode, various conductive materials such as Al, Ag, ITO,or ITO containing silicon can be used as the second electrode 107regardless of the magnitude of the work function.

Note that, for the layer having a function of promoting electroninjection, a compound of alkali metal or alkaline earth metal, such aslithium fluoride (LiF), cesium fluoride (CsF), or calcium fluoride(CaF₂) can be used. Alternatively, a layer formed of a substance havingan electron transport property, in which alkali metal or alkaline earthmetal is contained, for example, Alq in which magnesium (Mg) or lithium(Li) is contained, or the like can be used.

The first layer 103, the second layer 104, the third layer 105, and thefourth layer 106 may be formed by various methods such as an evaporationmethod, an ink-jet method, and a spin coating method. In addition,different methods may be separately used to form respective electrodesor layers.

In the light emitting element of the present invention having theabove-described structure, current flows due to a potential differencemade between the first electrode 102 and the second electrode 107; holesand electrons are recombined in the third layer 105 that is a layercontaining a substance with an excellent light emitting property; andthen, light is emitted. In other words, a light emitting region isformed in the third layer 105.

Light emission is extracted outside through either or both the firstelectrode 102 and the second electrode 107. Accordingly, either or boththe first electrode 102 and the second electrode 107 are formed of alight-transmitting substance. When only the first electrode 102 isformed of a light-transmitting substance, light emission is extractedfrom the substrate side through the first electrode 102 as shown in FIG.1A. When only the second electrode 107 is formed of a light-transmittingsubstance, light emission is extracted from the side opposite to thesubstrate through the second electrode 107 as shown in FIG. 1B. Whenboth the first electrode 102 and the second electrode 107 are formed ofa light-transmitting substance, light emission is extracted from boththe substrate side and the opposite side through the first electrode 102and the second electrode 107 as shown in FIG. 1C.

Note that a structure of layers provided between the first electrode 102and the second electrode 107 is not limited to the structure describedabove. Another structure may be employed as long as it has a structurein which a light emitting region where holes and electrons arerecombined with each other is provided in a portion apart from the firstelectrode 102 and the second electrode 107 so as to suppress quenchingcaused by approach of the light emitting region and metal.

In other words, a stacking structure of the layers is not particularlylimited, and the layers may be structured by freely combining layersformed of a substance having an excellent electron transport property, asubstance having an excellent hole transport property, a substancehaving an excellent electron injection property, a substance having anexcellent hole injection property, a substance having a bipolar property(a substance having an excellent electron and hole transport property),a hole blocking material, and the like with the aromatic amine compoundof the present invention.

A light emitting element shown in FIG. 2 has a structure in which afirst layer 303 formed of a substance having an excellent electrontransport property, a second layer 304 containing a light emittingsubstance, a third layer 305 formed of a substance having an excellenthole transport property, a fourth layer 306 formed of a substance havingan excellent hole injection property, and a second electrode 307functioning as an anode are sequentially stacked over a first electrode302 functioning as a cathode. Note that a reference numeral 301 denotesa substrate.

In this embodiment, the light emitting element is manufactured over asubstrate formed of glass, plastic, or the like. A passive-type lightemitting device can be manufactured by manufacturing a plurality of suchlight emitting elements over one substrate. Alternatively, for example,a thin film transistor (TFT) may be formed over a substrate formed ofglass, plastic, or the like, and a light emitting element may bemanufactured over an electrode which is electrically connected to theTFT. This makes it possible to manufacture an active matrix lightemitting device in which the drive of the light emitting element iscontrolled by the TFT. Note that the structure of the TFT is notparticularly limited. The TFT may be a staggered type or an invertedstaggered type. Furthermore, crystallinity of a semiconductor used forthe TFT is also not particularly limited, and either an amorphoussemiconductor or a crystalline semiconductor may be used. Moreover, adriver circuit formed over a TFT array substrate may include either ann-type TFT or a p-type TFT, or both of them.

The aromatic amine compound of the present invention is a materialhaving an excellent hole transport property. Therefore, when used for alight emitting element, a drive voltage of the light emitting elementcan be reduced, which leads to a reduction in power consumption.

In addition, the aromatic amine compound of the present invention has ahigh glass transition point. Therefore, when used for a light emittingelement, a light emitting element having excellent heat resistance canbe obtained.

Furthermore, the aromatic amine compound of the present invention isstable even when it is repeatedly subjected to oxidation reaction andsubsequent reduction reaction. In other words, it has stability inrepetitive oxidation reactions. Therefore, a long-life light emittingelement can be obtained by using the aromatic amine compound of thepresent invention for a light emitting element.

Embodiment 3

In this embodiment, a light emitting element having a structuredifferent from that described in Embodiment 2 is explained.

Since the aromatic amine compound of the present invention is asubstance having an excellent hole injection property, it can be usedfor the first layer 103 described in Embodiment 2. By using the aromaticamine compound of the present invention for the first layer 103, a lightemitting element with favorable characteristics can be obtained.

In the case of using the aromatic amine compound of the presentinvention for the first layer 103, various materials can be used as asubstance for forming the second layer 104. For example, an aromaticamine compound (that is, a compound having a benzene ring-nitrogen bond)can be used. A widely-used material is a star-burst aromatic aminecompound, for example,4,4′-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl, a derivative thereofsuch as 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (hereinafterreferred to as NPB), 4,4′,4″-tris(N,N-diphenyl-amino)triphenylamine, or4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine, or thelike. The substances described here are mainly substances having holemobility of 10⁻⁶ cm²/Vs or more. However, another substance may be usedas long as the substance has a more excellent hole transport propertythan electron transport property. Note that the second layer 104 may benot only a single layer but also a mixed layer of the above substancesor stacked layers of two or more layers.

In addition, the aromatic amine compound of the present invention may beused for the first layer 103 and the second layer 104.

The aromatic amine compound of the present invention is a materialhaving an excellent hole injection property. Therefore, when used for alight emitting element, a drive voltage of the light emitting elementcan be reduced, which leads to a reduction in power consumption.

In addition, the aromatic amine compound of the present invention has ahigh glass transition point. Therefore, when used for a light emittingelement, a light emitting element having excellent heat resistance canbe obtained.

In addition, the aromatic amine compound of the present invention isstable even when it is repeatedly subjected to oxidation reaction andsubsequent reduction reaction. In other words, it has stability inrepetitive oxidation reactions. Therefore, a long-life light emittingelement can be obtained by using the aromatic amine compound of thepresent invention for a light emitting element.

Note that the structure described in Embodiment 2 can be appropriatelyused except for the first layer 103.

Embodiment 4

In this embodiment, a light emitting element having a structuredifferent from that described in Embodiment 2 is explained.

By using the aromatic amine compound of the present invention for thethird layer 105 described in Embodiment 2, light emission from thearomatic amine compound of the present invention can be obtained. Sincethe aromatic amine compound of the present invention exhibits blue togreen light emission, a light emitting element which exhibits blue togreen light emission can be obtained.

The third layer 105 may be formed of only the aromatic amine compound ofthe present invention, or may be formed by dispersing the aromatic aminecompound of the present invention into another substance. As a substanceinto which the aromatic amine compound of the present invention isdispersed, various materials can be used. In place of the substancehaving an excellent hole transport property or the substance having anexcellent electron transport property described in Embodiment 2,4,4′-di(N-carbazolyl)biphenyl (abbr.: CBP),2,2′,2″-(1,3,5-benzenetri-yl)-tris[1-phenyl-1H-benzimidazolel] (abbr.:TPBI), 9,10-di(2-naphthyl)anthracene (abbr.: DNA),2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbr.: t-BuDNA), or the likecan be used.

The aromatic amine compound of the present invention has a high glasstransition point. Therefore, when used for a light emitting element, alight emitting element having excellent heat resistance can be obtained.

In addition, the aromatic amine compound of the present invention isstable even when it is repeatedly subjected to oxidation reaction andsubsequent reduction reaction. In other words, it has stability inrepetitive oxidation reactions. Therefore, a long-life light emittingelement can be obtained by using the aromatic amine compound of thepresent invention for a light emitting element.

Note that the structures described in Embodiments 2 and 3 can beappropriately used except for the third layer 103.

Embodiment 5

In this embodiment, a light emitting device which is manufactured usingthe aromatic amine compound of the present invention is explained.

In this embodiment, a light emitting device which is manufactured usingthe aromatic amine compound of the present invention is explained withreference to FIGS. 3A and 3B. Note that FIG. 3A is a top view showing alight emitting device and FIG. 3B is a cross-sectional view of FIG. 3Ataken along lines A-A′ and B-B′. A reference numeral 601 indicated bydashed line denotes a driver circuit portion (a source side drivercircuit); 602, a pixel portion; and 603, a driver circuit portion (agate side driver circuit). A reference numeral 604 denotes a sealingsubstrate; 605, a sealant; and a portion surrounded by the sealant 605is a space 607.

Note that a lead wiring 608 is a wiring for transmitting signals to beinputted to the source side driver circuit 601 and the gate side drivercircuit 603 and receives a video signal, a clock signal, a start signal,a reset signal, and the like from an FPC (flexible printed circuit) 609that is an external input terminal. Note that only the FPC is shownhere; however, the FPC may be provided with a printed wiring board(PWB). The light emitting device in this specification includes not onlya main body of the light emitting device but also a light emittingdevice with an FPC or a PWB attached.

Next, a cross-sectional structure is explained with reference to FIG.3B. The driver circuit portion and the pixel portion are formed over anelement substrate 610. Here, the source side driver circuit 601 that isthe driver circuit portion and one pixel in the pixel portion 602 areshown.

Note that a CMOS circuit that is a combination of an n-channel TFT 623and a p-channel TFT 624 is formed in the source side driver circuit 601.The driver circuit may be formed using a CMOS circuit, a PMOS circuit,or an NMOS circuit. A driver integration type in which a driver circuitis formed over a substrate is described in this embodiment, but it isnot necessarily required and a driver circuit can be formed not over asubstrate but outside a substrate.

The pixel portion 602 has a plurality of pixels, each of which includesa switching TFT 611, a current control TFT 612, and a first electrode613 which is electrically connected to a drain of the current controlTFT 612. Note that an insulator 614 is formed to cover an end of thefirst electrode 613. Here, a positive type photosensitive acrylic resinfilm is used.

The insulator 614 is formed to have a curved surface with curvature atan upper end or a lower end thereof in order to obtain favorablecoverage. For example, in the case of using positive type photosensitiveacrylic as a material of the insulator 614, the insulator 614 ispreferably formed to have a curved surface with a curvature radius (0.2μm to 3 μm) only at an upper end. Either a negative type which becomesinsoluble in an etchant by light irradiation or a positive type whichbecomes soluble in an etchant by light irradiation can be used as theinsulator 614.

A layer 616 containing a light emitting substance and a second electrode617 are formed over the first electrode 613. Here, a material having ahigh work function is preferably used as a material used for the firstelectrode 613 which functions as an anode. For example, the firstelectrode 613 can be formed by using a single-layer film such as an ITOfilm, an indium tin oxide film containing silicon, an indium oxide filmcontaining zinc oxide of 2 wt % to 20 wt %, a titanium nitride film, achromium film, a tungsten film, a Zn film, or a Pt film; a stacked layerof a titanium nitride film and a film containing aluminum as its maincomponent; a three-layer structure of a titanium nitride film, a filmcontaining aluminum as its main component, and a titanium nitride film;or the like. When the first electrode 613 has a stacked-layer structure,it can have low resistance as a wiring and form a favorable ohmiccontact. Further, the first electrode can function as an anode.

The layer 616 containing a light emitting substance is formed by variousmethods such as an evaporation method using an evaporation mask, anink-jet method, and a spin coating method. The layer 616 containing alight emitting substance contains the aromatic amine compound of thepresent invention described in Embodiment 1. Further, another materialincluded in the layer 616 containing a light emitting substance may be alow molecular material, an intermediate molecular material (including anoligomer and a dendrimer), or a high molecular material. In addition, asa material used for the layer containing a light emitting substance, asingle layer or a stacked layer of an organic compound is generallyused. However, the present invention also includes a structure in whichan inorganic compound is used for a part of a film formed of the organiccompound.

As a material used for the second electrode 617 which is formed over thelayer 616 containing a light emitting substance and functions as acathode, a material having a low work function (Al, Mg, Li, Ca, an alloyor a compound thereof such as MgAg, MgIn, AlLi, LiF, or CaF₂, or thelike) is preferably used. In the case where light generated in the layer616 containing a light emitting substance is transmitted through thesecond electrode 617, a stacked layer of a metal thin film with a thinthickness and a transparent conductive film (of ITO, indium oxidecontaining zinc oxide of 2 wt % to 20 wt %, indium tin oxide containingsilicon, zinc oxide (ZnO), or the like) is preferably used as the secondelectrode 617.

By attaching the sealing substrate 604 to the element substrate 610 withthe sealant 605, a light emitting element 618 is provided in the space607 surrounded by the element substrate 610, the sealing substrate 604,and the sealant 605. Note that the space 607 is filled with a filler,but there is also a case where the space 607 is filled with the sealant605 or filled with an inert gas (nitrogen, argon, or the like).

Note that an epoxy-based resin is preferably used as the sealant 605.The material preferably allows as little moisture and oxygen as possibleto penetrate. As the sealing substrate 604, a plastic substrate formedof FRP (Fiberglass-Reinforced Plastics), PVF (polyvinyl fluoride),Myler, polyester, acrylic, or the like can be used besides a glasssubstrate or a quartz substrate.

As described above, the light emitting device which is manufacturedusing the aromatic amine compound of the present invention can beobtained.

Since the aromatic amine compound described in Embodiment 1 is used forthe light emitting device of the present invention, a light emittingdevice having favorable characteristics can be obtained. Specifically, alight emitting device having high heat resistance can be obtained.

In addition, since the aromatic amine compound of the present inventionis a material having an excellent hole transport property, a drivevoltage of the light emitting element can be reduced and powerconsumption of the light emitting device can be reduced.

Furthermore, the aromatic amine compound of the present invention isstable even when it is repeatedly subjected to oxidation reaction andsubsequent reduction reaction. In other words, it has stability inrepetitive oxidation reaction. Therefore, a long-life light emittingdevice can be obtained by using the aromatic amine compound of thepresent invention for a light emitting device.

As described above, an active-type light emitting device in which driveof a light emitting element is controlled by a transistor is explainedin this embodiment. However, a passive-type light emitting device inwhich the light emitting element is driven without particularlyproviding a driver element such as a transistor may also be employed.FIG. 4 shows a perspective view of a passive-type light emitting devicewhich is manufactured by applying the present invention. In FIG. 4, alayer 955 containing a light emitting substance is provided between anelectrode 952 and an electrode 956 over a substrate 951. An end portionof the electrode 952 is covered with an insulating layer 953. Apartition layer 954 is provided over the insulating layer 953. Sidewalls of the partition layers 954 slope so that a distance between oneside wall and another side wall becomes narrow toward a substratesurface. In other words, a cross section of the partition layer 954 inthe direction of a narrow side is trapezoidal, and a base (a side facingin the same direction as a plane direction of the insulating layer 953and in contact with the insulating layer 953) is shorter than an upperside (a side facing in the same direction as the plane direction of theinsulating layer 953 and not in contact with the insulating layer 953).A defect of the light emitting element due to static electricity or thelike can be prevented by providing the partition layer 954 in thismanner. In addition, the passive-type light emitting device can also bedriven with less power consumption when it includes the light emittingelement of the present invention which operates at low drive voltage.

Embodiment 6

In this embodiment, an electronic device of the present invention whichincludes the light emitting device described in Embodiment 5 as acomponent is explained. The electronic device of the present inventioncontains the aromatic amine compound of the present invention describedin Embodiment 1 and has a display portion with high heat resistance. Italso has a display portion with long life. Further, it has a displayportion which consumes less power.

Examples of an electronic device having a light emitting elementmanufactured using the aromatic amine compound of the present inventioncan be given as follows: a camera such as a video camera or a digitalcamera, a goggle type display, a navigation system, a sound reproducingdevice (car audio, an audio component, or the like), a computer, a gamemachine, a portable information terminal (a mobile computer, a cellularphone, a portable game machine, an electronic book, or the like), animage reproducing device provided with a recording medium (specifically,a device which can reproduce a recording medium such as a digitalversatile disc (DVD) and includes a display device capable of displayingimages thereof), and the like. Specific examples of them are shown inFIGS. 5A to 5D.

FIG. 5A shows a television device according to the present invention,which includes a chassis 9101, a support 9102, a display portion 9103, aspeaker portion 9104, a video input terminal 9105, and the like. In thistelevision device, the display portion 9103 includes light emittingelements which are similar to those described in Embodiments 2 to 4 andarranged in matrix. The light emitting element is characterized by lowvoltage drive and long life. In addition, it is characterized by highheat resistance. The display portion 9103 which includes the lightemitting elements also has a similar feature. Therefore, in thistelevision device, image quality is hardly deteriorated and a reductionin power consumption is achieved. With such features, a deteriorationcompensation function and a power supply circuit can be significantlyremoved or reduced in the television device, thereby achievingreductions in size and weight of the chassis 9101 and the support 9102.Since a reduction in power consumption, an improvement in image quality,and reductions in size and weight are achieved in the television deviceaccording to the present invention, a product which is suitable forliving environment can be provided.

FIG. 5B shows a computer according to the present invention, whichincludes a main body 9201, a chassis 9202, a display portion 9203, akeyboard 9204, an external connection port 9205, a pointing mouse 9206,and the like. In this computer, the display portion 9203 includes lightemitting elements which are similar to those described in Embodiments 2to 4 and arranged in matrix. The light emitting element is characterizedby low voltage drive and long life. In addition, it is characterized byhigh heat resistance. The display portion 9203 which includes the lightemitting elements has a similar feature. Therefore, in this computer,image quality is hardly deteriorated and a reduction in powerconsumption is achieved. With such features, a deteriorationcompensation function and a power supply circuit can be significantlyremoved or reduced in the computer, thereby achieving reductions in sizeand weight of the main body 9201 and the chassis 9202. Since a reductionin power consumption, an improvement in image quality, and reductions insize and weight thereof are achieved in the computer according to thepresent invention, a product which is suitable for living environmentcan be provided.

FIG. 5C shows a cellular phone according to the present invention, whichincludes a main body 9401, a chassis 9402, a display portion 9403, anaudio input portion 9404, an audio output portion 9405, an operation key9406, an external connection port 9407, an antenna 9408, and the like.In this cellular phone, the display portion 9403 includes light emittingelements which are similar to those described in Embodiments 2 to 4 andarranged in matrix. The light emitting element is characterized by lowvoltage drive and long life. It is also characterized by high heatresistance. The display portion 9403 which includes the light emittingelements also has a similar feature. Therefore, in this cellular phone,image quality is hardly deteriorated and a reduction in powerconsumption is achieved. With such features, a deteriorationcompensation function and a power supply circuit can be significantlyremoved or reduced in the cellular phone, thereby achieving reductionsin size and weight of the main body 9401 and the chassis 9402. Since areduction in power consumption, an improvement in image quality, andreductions in size and weight thereof are achieved in the cellular phoneaccording to the present invention, a product which is suitable forbeing carried can be provided.

FIG. 5D shows a camera according to the present invention, whichincludes a main body 9501, a display portion 9502, a chassis 9503, anexternal connection port 9504, a remote control receiving portion 9505,an image receiving portion 9506, a battery 9507, an audio input portion9508, an operation key 9509, an eye piece portion 9510, and the like. Inthis camera, the display portion 9502 includes light emitting elementswhich are similar to those described in Embodiments 2 to 4 and arrangedin matrix. The light emitting element is characterized by low voltagedrive and long life. It is also characterized by high heat resistance.The display portion 9502 which includes the light emitting elements alsohas similar features. Therefore, in this camera, image quality is hardlydeteriorated and a reduction in power consumption is achieved. With suchfeatures, a deterioration compensation function and a power supplycircuit can be significantly removed or reduced in the camera, therebyachieving reductions in size and weight of the main body 9501. Since areduction in power consumption, an improvement in image quality, andreductions in size and weight thereof are achieved in the cameraaccording to the present invention, a product which is suitable forbeing carried can be provided.

As described above, the applicable range of the light emitting device ofthe present invention is so wide that this light emitting device can beapplied to electronic devices of various fields. By using the aromaticamine compound of the present invention, an electronic device includinga display portion which consumes less power, has a long life, and hashigh heat resistance can be provided.

In addition, the light emitting device of the present invention can beused as a lighting system. One mode of using the light emitting elementof the present invention as a lighting system is explained withreference to FIG. 6.

FIG. 6 shows an example of a liquid crystal display device using thelight emitting device of the present invention as a backlight. Theliquid crystal display device shown in FIG. 6 includes a chassis 901, aliquid crystal layer 902, a backlight 903, and a chassis 904. The liquidcrystal layer 902 is connected to a driver IC 905. The light emittingdevice of the present invention is used as the backlight 903, to which acurrent is supplied through a terminal 906.

By using the light emitting device of the present invention as abacklight of a liquid crystal display device, a backlight which consumesless power can be obtained. Since the light emitting device of thepresent invention is a plane-emission lighting system and can be formedto have a large area, a larger-area backlight can be obtained and alarger-area liquid crystal display device can also be obtained.Furthermore, the light emitting device of the present invention is thinand consumes less power; therefore, reductions in thickness and powerconsumption of the display device can also be achieved. Moreover, sincethe light emitting device of the present invention has a long life andexcellent heat resistance, a liquid crystal display device also has along life and excellent heat resistance.

EXAMPLE 1

A method for synthesizingN,N′,N″-triphenyl-N,N′,N″-tris(9-phenylcarbazol-3-yl)-benzene-1,3,5-triamine(abbr.: PCA3B) represented by Structural Formula (21) as an example ofthe aromatic amine compound of the present invention is explained.

[Step 1]

First, a method for synthesizing 3-bromo-9-phenylcarbazole is explained.A synthetic scheme of 3-bromo-9-phenylcarbazole is shown in (B-1).

24.3 g (100 mmol) of 9-phenylcarbazole was dissolved in 600 mL of aglacial acetic acid, 17.8 g (100 mmol) of N-bromosuccinimide wasgradually added thereto, and the mixture was stirred for approximately20 hours at a room temperature. This glacial acetic acid solution wasdropped into 1 L of ice water while stirring. The precipitated whitesolid was washed with water three times. This solid was dissolved in 150mL of diethyl ether and the solution was washed with a saturated aqueoussodium hydrogen carbonate solution and water. An organic layer thereofwas dried with magnesium sulfate. The organic layer was filtered, andthe obtained filtrate was concentrated, where about approximately 50 mLof methanol was added and dissolved uniformly. The white solid wasprecipitated by leaving this solution at rest. This solid was recoveredand dried, thereby obtaining 28.4 g (yield: 88%) of3-bromo-9-phenylcarbazole as a white powder.

[Step 2]

Next, a method for synthesizing 3-(N-phenylamino)-9-phenylcarbazole(abbr.: PCA) is explained. A synthetic scheme of PCA is shown in (B-2).

After putting 19 g (60 mmol) of 3-bromo-9-phenylcarbazole, 340 mg (0.6mmol) of bis(dibenzylideneacetone)palladium(0), 1.6 g (3.0 mmol) of1,1-bis(diphenylphosphino)ferrocene, and 13 g (180 mmol) of sodiumtert-butoxide into a three-neck flask and replacing the air in the flaskwith nitrogen, 110 mL of anhydrous xylene and 7.0 g (75 mmol) of anilinewere added. This was stirred for 7.5 hours while heating at 90° C. in anitrogen atmosphere. After the reaction, about 500 mL of hot toluene wasadded to the suspension and the mixture was filtered through florisil,alumina, and Celite®. The obtained filtrate was concentrated andhexane-ethyl acetate was added thereto, and then the mixture wasirradiated with ultrasonic waves. The obtained suspension was filteredand the residue was dried, thereby obtaining 15 g (yield: 75%) of3-(N-phenylamino)-9-phenylcarbazole (abbr.: PCA) as a cream-coloredpowder.

A result of proton nuclear magnetic resonance spectrometry (¹H NMR)analysis is as follows. ¹H NMR (300 MHz, CDCl₃); 67 =5.69 (s, 1H), 6.84(t, J=6.9 Hz, 1H), 6.97 (d, J=7.8 Hz, 2H), 7.20-7.61 (m, 12H), 7.90 (s,1H), 8.04 (d, J=7.8 Hz, 1H). FIG. 7A shows a ¹H NMR chart, and FIG. 7Bshows an enlarged view of FIG. 7A in a portion of 5.0 ppm to 9.0 ppm.

In addition, a result of nuclear magnetic resonance spectrometryanalysis when using DMSO as a solvent is shown. ¹H NMR (300 MHz,DMSO-d₆); δ=6.73 (t, J=7.5 Hz, 1H), 7.02 (d, J=8.1 Hz, 2H), 7.16-7.70(m, 12H), 7.95 (s, 1H), 8.06 (s, 1H), 8.17 (d, J=7.8 Hz, 1H). ¹³C NMR(75.5 MHz, DMSO-d₆); δ=109.55, 110.30, 110.49, 114.71, 118.22, 119.70,120.14, 120.61, 122.58, 123.35, 126.18, 126.48, 127.37, 129.15, 130.14,135.71, 136.27, 137.11, 140.41, 145.61.

[Step 3]

Next, a method for synthesizingN,N′,N″-triphenyl-N,N′,N″-tris(9-phenylcarbazol-3-yl)-benzene-1,3,5-triamine(abbr.: PCA3B) represented by Structural Formula (21) is explained. Asynthetic scheme of PCA3B is shown in (B-3).

After putting 1.9 g (6.0 mmol) of 1,3,5-tribromobenzene, 6.4 g (19 mmol)of PCA obtained in Step 2, 580 mg (1.0 mmol) ofbis(dibenzylideneacetone)palladium(0), and 4.0 g (40 mmol) of sodiumtert-butoxide into a three-neck flask and replacing the air in the flaskwith nitrogen, 30 mL of anhydrous xylene was added and the mixture wasdeaerated for 3 minutes until no more bubble comes out. 6.0 mL (3.0mmol) of tri(tert-butyl)phosphine (a 10 wt % hexane solution) was added,and the mixture was stirred in a nitrogen atmosphere while heating at90° C. After 3.5 hours, heating was stopped and about 500 mL of toluenewas added to this reaction solution, and the mixture was filteredthrough florisil and Celite®. The obtained filtrate was washed withwater and dried by adding magnesium sulfate. This solution was filtered;the obtained filtrate was concentrated and separated by silica gelcolumn chromatography (toluene: hexane=2:3). The obtained solution wasconcentrated; hexane was added; and the mixture was irradiated withultrasonic waves. The produced solid was filtered off and dried, therebyobtaining 2.0 g (yield: 34%) ofN,N′,N″-triphenyl-N,N′,N″-tris(9-phenylcarbazol-3-yl)-benzene-1,3,5-triamine(abbr.: PCA3B) as a light bright golden yellow powder.

A result of proton nuclear magnetic resonance spectrometry (¹H NMR)analysis is as follows. ¹H NMR (300 MHz, DMSO-d₆); 67 =6.21 (s, 3H),6.78 (t, J=6.9 Hz, 3H), 6.99-7.21 (m, 21H), 7.29 (d, J=8.4 Hz, 3H),7.37-7.53 (m, 12H), 7.61 (t, J=7.8, 6H), 7.96 (d, J=1.5 Hz, 3H), 8.16(d, J=7.5 Hz, 3H). FIG. 8A shows a ¹H NMR chart, and FIG. 8B shows anenlarged view of FIG. 8A in a portion of 6.0 ppm to 8.5 ppm.

In addition, a glass transition point was measured using a differentialscanning calorimeter (DSC, manufactured by Perkin Elmer Co., Ltd., Pyris1). First, a sample was heated to 440° C. at 40° C./min and then cooledto a room temperature at 40° C./min. Subsequently, the temperature israised to 440° C. at 10° C./min and cooled to a room temperature at 40°C./min, thereby obtaining a DSC chart of FIG. 11. This chart shows thata glass transition point (Tg) of PCA3B is 146° C. This indicates thatPCA3B has a high glass transition point. Note that in this measurement,a heat absorption peak which indicates a melting point was not observed.

Absorption spectra of a toluene solution of PCA3B and a thin film ofPCA3B are shown in FIG. 9. An ultraviolet-visible spectrophotometer(V-550, manufactured by JASCO Corporation) was used for the measurement.The solution was put in a quartz cell and the thin film was evaporatedover a quartz substrate as samples, and absorption spectra of them, fromwhich an absorption spectrum of quartz was subtracted, are shown in FIG.9. In FIG. 9, the horizontal axis indicates wavelength (nm) and thevertical axis indicates absorption intensity (arbitrary unit).Absorption was observed at around 311 nm and 370 nm in the case of thetoluene solution, and at around 316 nm and 380 nm in the case of thethin film. Emission spectra of the toluene solution (excitationwavelength: 320 nm) of PCA3B and the thin film (excitation wavelength:311 nm) of PCA3B are shown in FIG. 10. In FIG. 10, the horizontal axisindicates wavelength (nm) and the vertical axis indicates emissionintensity (arbitrary unit). The maximum emission wavelength was 416 nm(excitation wavelength: 320 nm) in the case of the toluene solution and437 nm (excitation wavelength: 311 nm) in the case of the thin film.

As a result of measuring the HOMO level of PCA3B in a thin-film state byusing a photoelectron spectrometer (AC-2, manufactured by Riken KeikiCo., Ltd.) in the atmosphere, it was −5.31 eV. Furthermore, as a resultof obtaining an absorption edge from a Tauc plot using data of theabsorption spectrum of the thin film of PCA3B in FIG. 9 and evaluatingthe absorption edge as an optical energy gap, the energy gap was 2.99 eVThus, the LUMO level is −2.32 eV.

In addition, an oxidation reaction characteristic of PCA3B was measured.The oxidation reaction characteristic was examined by a cyclicvoltammetry (CV) measurement. Note that an electrochemical analyzer (ALSmodel 600A, manufactured by BAS Inc.) was used for the measurement.

As for a solution used in the CV measurement, anhydrousdimethylformamide (DMF) (manufactured by Aldrich Chemical Company,99.8%, catalog number: 22705-6) was used as a solvent.Tetra-n-butylammonium perchlorate (n-Bu₄NClO₄) (manufactured by TokyoChemical Industry Co., Ltd., catalog number: T0836), which was asupporting electrolyte, was dissolved in the solvent so that theconcentration of the tetra-n-butylammonium perchlorate was 100 mmol/L.Further, an object to be measured was dissolved therein so that theconcentration thereof was 1 mmol/L. Thus, the solution was prepared.Further, a platinum electrode (PTE platinum electrode, manufactured byBAS Inc.) was used as a work electrode. A platinum electrode (VC-3 Ptcounter electrode (5 cm), manufactured by BAS Inc.) was used as anauxiliary electrode. An Ag/Ag⁺ electrode (RE 5 nonaqueous referenceelectrode, manufactured by BAS Inc.) was used as a reference electrode.Note that the measurement was carried out at a room temperature.

The oxidation reaction characteristic of PCA3B was examined as follows.A scan for changing a potential of the work electrode with respect tothe reference electrode from 0.9 V to −0.04 V after changing it from−0.04 V to 0.9 V was regarded as one cycle, and measurement wasperformed for 100 cycles. Note that a scan rate of the CV measurementwas set to be 0.1 V/s.

Results of examining the oxidation reaction characteristic of PCA3B areshown in FIG. 12. In FIG. 12, the horizontal axis indicates a potential(V) of the work electrode with respect to the reference electrode,whereas the vertical axis indicates the value of current flowing betweenthe work electrode and the auxiliary electrode (1×10⁻⁵ A).

According to FIG. 12, currents indicating oxidation were observed ataround 0.4 V, 0.5 V, and 0.6 V (vs. Ag/Ag⁺ electrode). Although thescanning was repeated for 100 cycles, changes in peak position and peakintensity of a CV curve were hardly seen in the oxidation reaction.Accordingly, it was found that the aromatic amine compound of thepresent invention was extremely stable with respect to oxidationreaction and subsequent reduction reaction (that is, the repetition ofoxidation).

COMPARATIVE EXAMPLE 1

As a comparative example, a glass transition point of1,3,5-tris{N-(4-diphenylaminophenyl)amino}benzene described in Reference1 was measured.

The glass transition point was measured using a differential scanningcalorimeter (DSC, manufactured by Perkin Elmer Co., Ltd., Pyris 1)similarly to Example 1. First, a sample was melted by being heated to350° C. at 40° C./min and was then cooled to a room temperature at 40°C./min. Subsequently, the temperature was raised to 350° C. at 10°C./min and cooled to a room temperature at 40° C./min, thereby obtaininga DSC chart of FIG. 37. This chart shows that a glass transition point(Tg) of 1,3,5-tris{N-(4-diphenylaminophenyl)amino}benzene is 106° C.Note that in the DSC chart at the time when the sample was first melted,a heat absorption peak indicating a melting point was observed, and themelting point was 236° C. Note that it is described in Reference 1 thatthe glass transition point is 108° C. and the melting point is 240° C.

Accordingly, it is found that the aromatic amine compound of the presentinvention has a higher glass transition point than1,3,5-tris{N-(4-diphenylaminophenyl)amino}benzene described in Reference1 and has excellent heat resistance.

EXAMPLE 2

A method for synthesizing

N,N′-bis(9-phenylcarbazol-3-yl)-N,N′-diphenyl-benzene-1,3-diamine(abbr.: PCA2B) represented by Structural Formula (51) as an example ofthe aromatic amine compound of the present invention is explained.

[Step 1]

A method for synthesizing PCA2B is explained. A synthetic scheme ofPCA2B is shown in (B-4).

After putting 1.18 g (5.0 mmol) of 1,3-dibromobenzene, 3.3 g (10 mmol)of PCA synthesized in Step 2 of Example 1, 580 mg (1.0 mmol) ofbis(dibenzylideneacetone)palladium(0), and 3.0 g (30 mmol) of sodiumtert-butoxide into a three-neck flask and replacing the air in the flaskwith nitrogen, 20 mL of anhydrous xylene was added thereto and themixture was deaerated for 3 minutes until no more bubble comes out. 6 mL(3 mmol) of tri(tert-butyl)phosphine (a 10 wt % hexane solution) wasadded, and the mixture was stirred in a nitrogen atmosphere whileheating at 90° C. After 5.0 hours, heating was stopped, and about 200 mLof toluene was added to this reaction solution, and the solution wasfiltered through florisil and Celite®. The obtained filtrate was washedwith water and dried by adding magnesium sulfate. This solution wasfiltered; the obtained filtrate was concentrated and separated by silicagel column chromatography (toluene:hexane=2:3). The obtained solutionwas concentrated; hexane was added; and the mixture was irradiated withultrasonic waves. The produced solid was filtered off and dried, therebyobtaining 2.0 g (yield: 54%) ofN,N′-bis(9-phenylcarbazol-3-yl)-N,N′-diphenyl-benzene-1,3-diamene(abbr.: PCA2B). as a light-cream-colored powder.

A result of proton nuclear magnetic resonance spectrometry (¹H NMR)analysis is as follows. ¹H NMR (300 MHz, CDCl₃); δ=6.65 (dd, J=8.1 Hz,2.1 Hz, 2H), 6.83-6.88 (m, 2H), 6.98 (t, J=2.1 Hz, 1H), 7.03-7.28 (m,15H), 7.37 (d, J=3.3 Hz, 4H), 7.42-7.60 (m, 10H), 7.90 (d, J=2.1 Hz,2H), 7.98 (d, J=7.8 Hz, 2H). FIG. 13A shows a ¹H NMR chart, and FIG. 13Bshows an enlarged view of FIG. 13A in a portion of 6.0 ppm to 8.5 ppm.

In addition, a glass transition point was measured using a differentialscanning calorimeter (DSC, manufactured by Perkin Elmer Co., Ltd., Pyris1). First, a sample was heated to 400° C. at 40° C./min and then cooledto a room temperature at 40° C./min. Subsequently, the temperature wasraised to 400° C. at 10° C./min and cooled to a room temperature at 40°C./min, thereby obtaining a DSC chart of FIG. 16. This chart shows thata glass transition point (Tg) of PCA2B is 124° C. This indicates thatPCA2B has a high glass transition point. Note that in this measurement,a heat absorption peak which indicates a melting point was not observed.

FIG. 14 shows absorption spectra of a toluene solution of PCA2B and athin film of PCA2B. An ultraviolet-visible spectrophotometer (V-550,manufactured by JASCO Corporation) was used for the measurement. Thesolution was put in a quartz cell and the thin film was evaporated overa quartz substrate as samples, and absorption spectra of them, fromwhich an absorption spectrum of quartz was subtracted, are shown in FIG.14. In FIG. 14, the horizontal axis indicates wavelength (nm) and thevertical axis indicates absorption intensity (arbitrary unit).Absorption was observed at around 309 nm and 370 nm in the case of thetoluene solution, and at around 311 nm and 380 nm in the case of thethin film. Emission spectra of the toluene solution (excitationwavelength: 325 nm) of PCA2B and the thin film (excitation wavelength:311 nm) of PCA2B are shown in FIG. 15. In FIG. 15, the horizontal axisindicates wavelength (nm) and the vertical axis indicates emissionintensity (arbitrary unit). The maximum emission wavelength was 422 nm(excitation wavelength: 325 nm) in the case of the toluene solution, and435 nm (excitation wavelength: 311 nm) in the case of the thin film.

As a result of measuring the HOMO level in a thin-film state by using aphotoelectron spectrometer (AC-2, manufactured by Riken Keiki Co., Ltd.)in the atmosphere, it was −5.28 eV. Furthermore, as a result ofobtaining an absorption edge from a Tauc plot using data of theabsorption spectrum of the thin film of PCA2B in FIG. 14 and evaluatingthe absorption edge as an optical energy gap, the energy gap was 2.98eV. Thus, the LUMO level is −2.30 eV.

In addition, an oxidation reaction characteristic of PCA2B was measured.The oxidation reaction characteristic was examined by a cyclicvoltammetry (CV) measurement. Note that an electrochemical analyzer (ALSmodel 600A, manufactured by BAS Inc.) was used for the measurement.

As for a solution used in the CV measurement, anhydrousdimethylformamide (DMF) (manufactured by Aldrich Chemical Company,99.8%, catalog number: 22705-6) was used as a solvent.Tetra-n-butylammonium perchlorate (n-Bu₄NClO₄) (manufactured by TokyoChemical Industry Co., Ltd., catalog number: T0836), which was asupporting electrolyte, was dissolved in the solvent so that theconcentration of the tetra-n-butylammonium perchlorate was 100 mmol/L.Further, an object to be measured was dissolved therein so that theconcentration thereof was 1 mmol/L. Thus, the solution was prepared.Further, a platinum electrode (PTE platinum electrode, manufactured byBAS Inc.) was used as a work electrode. A platinum electrode (VC-3 Ptcounter. electrode (5 cm), manufactured by BAS Inc.) was used as anauxiliary electrode. An Ag/Ag⁺ electrode (RE 5 nonaqueous referenceelectrode, manufactured by BAS Inc.) was used as a reference electrode.Note that the measurement was carried out at a room temperature.

The oxidation reaction characteristic of PCA2B was examined as follows.A scan for changing a potential of the work electrode with respect tothe reference electrode from 0.7 V to 0.05 V after changing it from 0.05V to 0.7 V, was regarded as one cycle, and measurement was performed for100 cycles. Further, a scan rate of the CV measurement was set to be 0.1V/s.

Results of examining the oxidation reaction characteristic of PCA2B areshown in FIG. 17. In FIG. 17, the horizontal axis indicates a potential(V) of the work electrode with respect to the reference electrode,whereas the vertical axis indicates the value of current flowing betweenthe work electrode and the auxiliary electrode (1×10⁻⁵ A).

According to FIG. 17, a current indicating oxidation was observed ataround 0.4 V (vs. Ag/Ag⁺ electrode). Although the scanning was repeatedfor 100 cycles, changes in peak position and peak intensity of a CVcurve were hardly seen in the oxidation reaction. Accordingly, it wasfound that the aromatic amine compound of the present invention wasextremely stable with respect to oxidation reaction and subsequentreduction reaction (that is, repetition of oxidation).

EXAMPLE 3

This example explains a light emitting element of the present inventionwith reference to FIG. 30.

First, a film of indium tin oxide containing silicon oxide was formedover a glass substrate 2101 by a sputtering method, thereby forming afirst electrode 2102. Note that a thickness thereof was 110 nm and anelectrode area was 2 mm×2 mm.

Next, the substrate, over which the first electrode was formed, wasfixed to a substrate holder in a vacuum evaporation apparatus so thatthe side, on which the first electrode was formed, faced downward.Subsequently, a layer 2103 containing a composite material of an organiccompound and an inorganic compound was formed by co-evaporating NPB andmolybdenum oxide (VI) over the first electrode 2102 after evacuating thevacuum evaporation apparatus and reducing a pressure to approximately10⁻⁴ Pa. The thickness of the first electrode 2103 was adjusted to be 50nm and a weight ratio of NPB to molybdenum oxide (VI) was adjusted to be4:1 (=NPB:molybdenum oxide). Note that the co-evaporation method is anevaporation method by which evaporation is performed simultaneously froma plurality of evaporation sources in one treatment chamber.

Next, the aromatic amine compound of the present invention,N,N′,N″-triphenyl-N,N′,N″-tris(9-phenylcarbazol-3-yl)-benzene-1,3,5-triamine(abbr.: PCA3B) represented by Structural Formula (21) was formed overthe layer 2103 containing a composite material by a resistance-heatingevaporation method so as to have a thickness of 10 nm, thereby forming ahole transport layer 2104.

Furthermore, a light emitting layer 2105 with a thickness of 40 nm wasformed over the hole transport layer 2104 by co-evaporating Alq andcoumarin 6. Here, a weight ratio of Alq to coumarin 6 was adjusted to be1:0.01 (=Alq:coumarin 6). This caused coumarin 6 to be dispersed in thelayer formed of Alq.

After that, a film of Alq was formed over the light emitting layer 2105using a resistance-heating evaporation method so as to have a thicknessof 10 nm, thereby forming an electron transporting layer 2106.

Moreover, an electron injection layer 2107 with a thickness of 20 nm wasformed by co-evaporating Alq and lithium over the electron transportlayer 2106. Here, a weight ratio of Alq to lithium was adjusted to be1:0.01 (=Alq:lithium). This caused lithium to be dispersed in the layerformed of Alq.

Lastly, a film of aluminum was formed over the electron injection layer2107 using a resistance-heating evaporation method so as to have athickness of 200 nm, thereby forming a second electrode 2108. Thus, alight emitting element of Example 3 was manufactured.

FIG. 18 shows a current density-luminance characteristic of the lightemitting element of Example 3. In addition, FIG. 19 shows avoltage-luminance characteristic. Further, FIG. 20 shows an emissionspectrum when a current of 1 mA is applied. As for the light emittingelement of Example 3, green light emission derived from coumarin 6 withCIE chromaticity coordinates (x, y)=(0.30, 0.63) was obtained with aluminance of 940 cd/m² by applying a voltage of 5.0 V.

As described above, a light emitting element with favorablecharacteristics was obtained by using the aromatic amine compound of thepresent invention for a hole transport layer.

EXAMPLE 4

This example explains a light emitting element of the present inventionwith reference to FIG. 30.

First, a film of indium tin oxide containing silicon oxide was formedover a glass substrate 2101 by a sputtering method, thereby forming afirst electrode 2102. Note that a thickness thereof was 110 nm and anelectrode area was 2 mm×2 mm.

Next, the substrate, over which the first electrode was formed, wasfixed to a substrate holder in a vacuum evaporation apparatus so thatthe side, on which the first electrode was formed, faced downward.Subsequently, a layer 2103 containing a composite material of an organiccompound and an inorganic compound was formed by co-evaporating NPB andmolybdenum oxide (VI) over the first electrode 2102 after evacuating thevacuum evaporation apparatus and reducing a pressure to approximately10⁻⁴ Pa. A thickness thereof was adjusted to be 50 nm and a weight ratioof NPB to molybdenum oxide (VI) was adjusted to be 4:1 (=NPB:molybdenumoxide). Note that the co-evaporation method is an evaporation method bywhich evaporation is performed simultaneously from a plurality ofevaporation sources in one treatment chamber.

Next, the aromatic amine compound of the present invention,N,N′,N″-triphenyl-N,N′,N″-tris(9-phenylcarbazol-3-yl)-benzene-1,3,5-triamine(abbr.: PCA3B) represented by Structural Formula (21) was formed overthe layer 2103 containing a composite material by a resistance-heatingevaporation method so as to have a thickness of 10 nm, thereby forming ahole transport layer 2104.

Furthermore, a light emitting layer 2105 with a thickness of 30 nm wasformed over the hole transport layer 2104 by co-evaporating9-[4-(N-carbazolyl)]phenyl-10-phenylanthracene (abbr.: CzPA) and9-(4-{N-[4-(9-carbazolyl)phenyl]-N-phenylamino}phenyl)-10-phenylanthracene(abbr.: YGAPA). Here, a weight ratio of CzPA to YGAPA was adjusted to be1:0.04 (=CzPA: YGAPA). This caused YGAPA to be dispersed in the layerformed of CzPA.

After that, a film of Alq was formed over the light emitting layer 2105using a resistance-heating evaporation method so as to have a thicknessof 10 nm, thereby forming an electron transport layer 2106.

Moreover, an electron injection layer 2107 with a thickness of 20 nm wasformed by co-evaporating Alq and lithium over the electron transportlayer 2106. Here, a weight ratio of Alq to lithium was adjusted to be1:0.01 (=Alq:lithium). This caused lithium to be dispersed in the layerformed of Alq.

Lastly, a film of aluminum was formed over the electron injection layer2107 using a resistance-heating evaporation method so as to have athickness of 200 nm, thereby forming a second electrode 2108. Thus, alight emitting element of Example 4 was manufactured.

FIG. 21 shows a current density-luminance characteristic of the lightemitting element of Example 4. In addition, FIG. 22 shows avoltage-luminance characteristic. Further, FIG. 23 shows an emissionspectrum when a current of 1 mA is applied. As for the light emittingelement of Example 4, blue light emission derived from YGAPA with CIEchromaticity coordinates (x, y)=(0.17, 0.19) was obtained with aluminance of 1060 cd/m² by applying a voltage of 6.4 V.

As described above, a light emitting element with favorablecharacteristics was obtained by using the aromatic amine compound of thepresent invention for a hole transport layer.

EXAMPLE 5

This example explains a light emitting element of the present inventionwith reference to FIG. 30.

First, a film of indium tin oxide containing silicon oxide was formedover a glass substrate 2101 by a sputtering method, thereby forming afirst electrode 2102. Note that a thickness thereof was 110 nm and anelectrode area was 2 mm×2 mm.

Next, the substrate, over which the first electrode was formed, wasfixed to a substrate holder in a vacuum evaporation apparatus so thatthe side, on which the first electrode was formed, faced downward.Subsequently, a layer 2103 containing a composite material of an organiccompound and an inorganic compound was formed by co-evaporating NPB andmolybdenum oxide (VI) over the first electrode 2102 after evacuating thevacuum evaporation apparatus and reducing a pressure to approximately10⁻⁴ Pa. A thickness thereof was adjusted to be 50 nm and a weight ratioof NPB to molybdenum oxide (VI) was adjusted to be 4:2 (=NPB:molybdenumoxide). Note that the co-evaporation method is an evaporation method bywhich evaporation is performed simultaneously from a plurality ofevaporation sources in one treatment chamber.

Next, the aromatic amine compound of the present invention,N,N′-bis(9-phenylcarbazol-3-yl)-N,N′-diphenyl-benzene-1,3-diamine(abbr.: PCA2B) represented by Structural Formula (51) was formed overthe layer 2103 containing a composite material by a resistance-heatingevaporation method so as to have a thickness of 10 nm, thereby forming ahole transport layer 2104.

Furthermore, a light emitting layer 2105 with a thickness of 40 nm wasformed over the hole transport layer 2104 by co-evaporating9-[4-(N-carbazolyl)phenyl]-10-phenylanthracene (abbr.: CzPA) and2,5,8,11-tetra(tert-butyl)perylene (abbr.: TBP). Here, a weight ratio ofCzPA to TBP was adjusted to be 1:0.01 (=CzPA:TBP). This caused TBP to bedispersed in the layer formed of CzPA.

After that, a film of Alq was formed over the light emitting layer 2105using a resistance-heating evaporation method so as to have a thicknessof 20 nm, thereby forming an electron transport layer 2106.

Moreover, a film of calcium fluoride was formed over the electrontransport layer 2106 so as to have a thickness of 1 nm, thereby formingan electron injection layer 2107.

Lastly, a film of aluminum was formed over the electron injection layer2107 using a resistance-heating evaporation method so as to have athickness of 200 nm, thereby forming a second electrode 2108. Thus, alight emitting element of Example 5 was manufactured.

FIG. 24 shows a current density-luminance characteristic of the lightemitting element of Example 5. In addition, FIG. 25 shows avoltage-luminance characteristic. Further, FIG. 26 shows an emissionspectrum when a current of 1 mA is applied. As for the light emittingelement of Example 5, light-blue light emission derived from TBP withCIE chromaticity coordinates (x, y)=(0.16, 0.24) was obtained with aluminance of 550 cd/m² by applying a voltage of 7.2 V.

As described above, a light emitting element with favorablecharacteristics was obtained by using the aromatic amine compound of thepresent invention for a hole transport layer.

EXAMPLE 6

This example explains a light emitting element of the present inventionwith reference to FIG. 30.

First, a film of indium tin oxide containing silicon oxide was formedover a glass substrate 2101 by a sputtering method, thereby forming afirst electrode 2102. Note that a thickness thereof was 110 nm and anelectrode area was 2 mm×2 mm.

Next, the substrate, over which the first electrode was formed, wasfixed to a substrate holder in a vacuum evaporation apparatus so thatthe side, on which the first electrode was formed, faced downward.Subsequently, a layer 2103 containing a composite material of an organiccompound and an inorganic compound was formed by co-evaporating NPB andmolybdenum oxide (VI) over the first electrode 2102 after evacuating thevacuum evaporation apparatus and reducing a pressure to approximately10⁻⁴ Pa. A thickness thereof was adjusted to be 50 nm and a weight ratioof NPB to molybdenum oxide (VI) was adjusted to be 4:2 (=NPB:molybdenumoxide). Note that the co-evaporation method is an evaporation method bywhich evaporation is performed simultaneously from a plurality ofevaporation sources in one treatment chamber.

Next, a film ofN,N′-bis(spiro-9,9′-bifluorene-2-yl)-N,N′-diphenylbenzidine (abbr.:BSPB) was formed over the layer 2103 containing a composite material bya resistance-heating evaporation method so as to have a thickness of 10nm, thereby forming a hole transport layer 2104.

Furthermore, the aromatic amine compound of the present invention,N,N′-bis(9-phenylcarbazol-3-yl)-N,N′-diphenyl-benzene-1,3-diamine(abbr.: PCA2B) represented by Structural Formula (51) was formed overthe hole transport layer 2104 so as to have a thickness of 30 nm,thereby forming a light emitting layer 2105.

After that, a film of BCP was formed over the light emitting layer 2105using a resistance-heating evaporation method so as to have a thicknessof 20 nm and a film of Alq is further formed so as to have a thicknessof 10 nm, thereby forming an electron transport layer 2106.

Moreover, a film of calcium fluoride was formed over the electrontransport layer 2106 so as to have a thickness of 1 nm, thereby formingan electron injection layer 2107.

Lastly, a film of aluminum was formed over the electron injection layer2107 using a resistance-heating evaporation method so as to have athickness of 200 nm, thereby forming a second electrode 2108. Thus, alight emitting element of Example 6 was manufactured.

FIG. 27 shows a current density-luminance characteristic of the lightemitting element of Example 6. In addition, FIG. 28 shows aluminance-voltage characteristic. Further, FIG. 29 shows an emissionspectrum when a current of 1 mA is applied. As for the light emittingelement of Example 6, blue light emission derived from PCA2B with CIEchromaticity coordinates (x, y)=(0.17, 0.12) was obtained with aluminance of 531 cd/m² by applying a voltage of 7.2 V.

As described above, a light emitting element with favorablecharacteristics was obtained by using the aromatic amine compound of thepresent invention for a light emitting layer.

EXAMPLE 7

A method for synthesizingN,N′,N″-triphenyl-N,N′,N″-tris[4-(carbazol-9-yl)phenyl]-benzene-1,3,5-triamine(abbr.: YGA3B) represented by Structural Formula (81) as an example ofthe aromatic amine compound of the present invention is explained.

[Step 1]

A method for synthesizing 9-[4-(N-phenylamino)phenyl]carbazole (abbr.:YGA) is explained.

(i) Synthesis of N-(4-bromophenyl)carbazole

Synthetic Scheme (D-1) of N-(4-bromophenyl)carbazole is shown below.

First, a method for synthesizing N-(4-bromophenyl)carbazole isexplained. 56.3 g (0.24 mol) of 1,4-dibromobenzene, 31.3 g (0.18 mol) ofcarbazole, 4.6 g (0.024 mol) of copper iodide, 66.3 g (0.48 mol) ofpotassium carbonate, and 2.1 g (0.008 mol) of 18-crown-6-ether were putinto a 300-mL three-neck flask and the air in the flask was replacedwith nitrogen. Then, 8 mL of1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (abbr.: DMPU) wasadded, and the mixture was stirred for 6 hours at 180° C. After coolingthe reaction mixture to a room temperature, the precipitate was removedby suction filtration. The filtrate was washed with a dilutedhydrochloric acid, a saturated aqueous sodium hydrogen carbonatesolution, and a saturated aqueous sodium chloride solution in thisorder, and then dried with magnesium sulfate. After drying, the reactionmixture was naturally filtered and concentrated, and the obtained oilysubstance was purified by silica gel column chromatography (hexane:ethylacetate=9:1) and recrystallized with chloroform and hexane, therebyobtaining 20.7 g of objective N-(4-bromophenyl)carbazole as alight-brown plate crystal with a yield of 35%.

¹H NMR of this compound is shown below. ¹H NMR (300 MHz, CDCl₃); δ=8.14(d, J=7.8 Hz, 2H), 7.73 (d, J=8.7 Hz, 2H), 7.46 (d, J=8.4 Hz, 2H),7.42-7.26 (m, 6H).

(ii) Synthesis of 9-[4-(N-phenylamino)phenyl]carbazole (abbr.: YGA)

Synthetic Scheme (D-2) of YGA is shown below.

5.4 g (17.0 mmol) of N-(4-bromophenyl)carbazole obtained in (i), 1.8 mL(20.0 mmol) of aniline, 100 mg (0.17 mmol) ofbis(dibenzylideneacetone)palladium(0), and 3.9 g (40 mmol) of sodiumtert-butoxide were put into a 200-mL three-neck flask and the air in theflask was replaced with nitrogen. Then, 0.1 mL oftri(tert-butyl)phosphine (a 10 wt % hexane solution) and 50 mL oftoluene were added, and the mixture was stirred for 6 hours at 80° C.The reaction mixture was filtered through florisil, Celite®, andalumina. The filtrate was washed with water and a saturated aqueoussodium chloride solution, and then dried with magnesium sulfate. Thereaction mixture was naturally filtered and the filtrate wasconcentrated, and the obtained oily substance was purified by silica gelcolumn chromatography (hexane:ethyl acetate=9:1), thereby obtaining 4.1g of objective 9-[4-(N-phenylamino)phenyl]carbazole (abbr.: YGA) with ayield of 73%. It was confirmed by nuclear magnetic resonance method(NMR) that this compound was 9-[4-(N-phenylamino)phenyl]carbazole(abbr.: YGA).

¹H NMR of this compound is shown below. In addition, ¹H NMR charts areshown in FIGS. 31A and 31B. Note that FIG. 31B is an enlarged chartshowing the range from 6.7 ppm to 8.6 ppm.

¹H NMR of this compound is shown below. ¹H NMR (300 MHz, DMSO-d₆);δ=8.47 (s, 1H), 8.22 (d, J=7.8 Hz, 2H), 7.44-7.16 (m, 14H), 6.92-6.87(m, 1H).

[Step 2]

Next, a method for synthesizingN,N′,N″-triphenyl-N,N′,N″-tris[4-(carbazol-9-yl)phenyl]-benzene-1,3,5-triamine(abbr.: YGA3B) represented by Structural Formula (81) is explained. Asynthetic scheme of YGA3B is shown in (D-3).

1.77 g (5.6 mmol) of 1,3,5-tribromobenzene, 5.68 g (17.0 mmol) of YGAobtained in the above Step 1, 58 mg (0.1 mol) ofbis(dibenzylideneacetone)palladium(0), 0.1 mL oftri(tert-butyl)phosphine (a 10 wt % hexane solution), and 5.0 g (52mmol) of sodium tert-butoxide were put into a 200-mL three-neck flaskand the air in the flask was replaced with nitrogen. Then, 50 mL oftoluene was added, and the mixture was stirred for 5 hours at 80° C.After the reaction, the reaction mixture was cooled to a roomtemperature and filtered through Celite®, florisil, and alumina. Thefiltrate was washed with water and a saturated aqueous sodium chloridesolution, and an organic layer was dried with magnesium sulfate.Magnesium sulfate was removed by natural filtration, and a white solidobtained by concentrating the filtrate was purified by silica gel columnchromatography (hexane:toluene=1:1) and recrystallized with chloroformand ethanol, thereby obtaining 4.6 g of objectiveN,N′,N″-triphenyl-N,N′,N″-tris[4-(carbazol-9-yl)phenyl]-benzene-1,3,5-triamine(abbr.: YGA3B) as a light-yellow powder solid with a yield of 77%.

A result of proton nuclear magnetic resonance spectrometry (¹H NMR)analysis of this compound is as follows. ¹H NMR (300 MHz, DMSO-d₆);δ=8.17 (d, J=7.20 Hz, 6H), 7.45-7.18 (m, 45H), 6.44 (s, 3H). Inaddition, ¹H NMR charts are shown in FIGS. 32A and 32B. Note that FIG.32B is an enlarged chart of FIG. 32A showing the range from 6.0 ppm to9.0 ppm.

EXAMPLE 8

A method for synthesizingN,N′-bis[4-(carbazol-9-yl)phenyl]-N,N′-diphenyl-benzene-1,3-diamine(abbr.: YGA2B) represented by Structural Formula (111) as an example ofthe aromatic amine compound of the present invention is explained.

[Step 1]

A method for synthesizing YGA2B is explained. A synthetic scheme ofYGA2B is shown in (D-4).

2.0 g (8.5 mmol) of 1,3-dibromobenzene, 5.68 g (17.0 mmol) of YGAobtained in Step 1 of Example 7, 58 mg (0.1 mol) ofbis(dibenzylideneacetone)palladium(0), 0.1 mL oftri(tert-butyl)phosphine (a 10 wt % hexane solution), and 5.0 g (52mmol) of sodium tert-butoxide were put into a 200-mL three-neck flaskand the air in the flask was replaced with nitrogen. Then, 50 mL oftoluene was added, and the mixture was stirred for 5 hours at 80° C.After the reaction, the precipitated solid was recovered by suctionfiltration, dissolved into toluene, and filtered through Celite®,florisil, and alumina. The filtrate was washed with water and asaturated aqueous sodium chloride solution, and an organic layer wasdried with magnesium sulfate. Magnesium sulfate was removed by naturalfiltration, and a white solid obtained by concentrating the filtrate wasrecrystallized with chloroform and hexane, thereby obtaining 5.5 g ofobjectiveN,N′-bis[4-(carbazol-9-yl)phenyl]-N,N′-diphenyl-benzene-1,3-diamine(abbr.: YGA2B) as a white solid with a yield of 88%.

A result of proton nuclear magnetic resonance spectrometry (¹H NMR)analysis of this compound is as follows. ¹H NMR (300 MHz, DMSO-d₆);δ=8.16 (d, J=6.30 Hz, 4H), 7.45-7.07 (m, 31H), 6.88 (s, 1H), 6.80 (d,J=8.40 Hz, 2H). In addition, ¹H NMR charts are shown in FIGS. 33A and33B. Note that FIG. 33B is an enlarged chart of FIG. 33A showing therange from 6.0 ppm to 9.0 ppm.

EXAMPLE 9

This example discloses a synthetic example of a substance used for thelight emitting element manufactured in any of the other examples.

Synthetic Example of YGAPA

Hereinafter, a method for synthesizing9-(4-{N-[4-(9-carbazolyl)phenyl)-N-phenylamino}phenyl)-10-phenylanthracene(abbr.: YGAPA) represented by Structural Formula (201) is explained.

[Step 1]

A method for synthesizing 9-phenyl-10-(4-bromophenyl)anthracene (abbr.:PA) is explained.

(i) Synthesis of 9-phenylanthracene

Synthetic Scheme (f-1) of 9-phenylanthracene is shown below.

5.4 g (21.1 mmol) of 9-bromoanthracene, 2.6 g (21.1 mmol) ofphenylboronic acid, 60 mg (0.21 mmol) of palladium acetate(II)(Pd(OAc)₂), 10 mL (20 mmol) of an aqueous potassium carbonate (K₂CO₃)solution (2 mol/L), 263 mg (0.84 mmol) of tri(o-tolyl)phosphine(P(o-tolyl)₃), and 20 mL of 1,2-dimethoxyethane (abbr.: DME) were mixedand stirred for 9 hours at 80° C. After the reaction, the precipitatedsolid was recovered by suction filtration, dissolved into toluene, andfiltered through florisil, Celite®, and alumina. The filtrate was washedwith a saturated aqueous sodium chloride solution and then dried withmagnesium sulfate. After natural filtration, the filtrate wasconcentrated, thereby obtaining 21.5 g of objective 9-phenylanthraceneas a light-brown solid with a yield of 85. %.

(ii) Synthesis of 10-bromo-9-phenylanthracene

Synthetic Scheme (f-2) of 10-bromo-9-phenylanthracene is shown below.

6.0 g (23.7 mmol) of 9-phenylanthracene was dissolved into 80 mL ofcarbon tetrachloride, and a solution in which 3.80 g (21.1 mmol) ofbromine was dissolved in 10 mL of carbon tetrachloride was dropped intothe reaction solution using a dropping funnel. After dropping, thesolution was stirred for 1 hour at a room temperature. After thereaction, an aqueous sodium thiosulfate solution was added to stop thereaction. An organic layer was washed with an aqueous sodium hydroxide(NaOH) solution and a saturated sodium chloride solution and dried withmagnesium sulfate. The mixture was naturally filtered, and a compoundobtained by concentrating the filtrate was dissolved into toluene andfiltered through florisil, Celite®, and alumina. The filtrate wasconcentrated and recrystallized with dichloromethane and hexane, therebyobtaining 7.0 g of objective 10-bromo-9-phenylanthracene as alight-yellow solid with a yield of 89%.

(iii) Synthesis of 9-iodo-10-phenylanthracene

Synthetic Scheme (f-3) of 9-iodo-10-phenylanthracene is shown below.

3.33 g (10 mmol) of 9-bromo-10-phenylanthracene was dissolved into 80mLof tetrahydrofuran (abbr.: THF) and cooled to −78° C., and then 7.5 mL(12.0 mmol) of n-BuLi (1.6 mol/L) was dropped into the reaction solutionusing a dropping funnel and stirred for 1 hour. A solution in which 5 g(20.0 mmol) of iodine was dissolved in 20 mL of THF was dropped andfurther stirred for 2 hours at −78° C. After the reaction, an aqueoussodium thiosulfate solution was added to stop the reaction. An organiclayer was washed with an aqueous sodium thiosulfate solution and asaturated sodium chloride solution and dried with magnesium sulfate.After natural filtration, the filtrate was concentrated, and theobtained solid was recrystallized with ethanol, thereby obtaining 3.1 gof objective 9-iodo-10-phenylanthracene as a light-yellow solid with ayield of 83%.

(iv) Synthesis of 9-phenyl-10-(4-bromophenyl)anthracene (abbr.: PA)

Synthetic Scheme (f-4) of 9-phenyl-10-(4-bromophenyl)anthracene (abbr.:PA) is shown below.

1.0 g (2.63 mmol) of 9-iodo-10-phenylanthracene, 542 mg (2.70 mmol) ofp-bromophenylboronic acid, 46 mg (0.03 mmol) oftetrakis(triphenylphosphine)palladium(0) (Pd(PPh₃)₄), 3 mL (6 mmol) ofan aqueous potassium carbonate (K₂CO₃) solution (2 mol/L), and 10 mL oftoluene were collected, mixed, and stirred for 9 hours at 80° C. Afterthe reaction, toluene was added and the mixture was filtered throughflorisil, Celite®, and alumina. The filtrate was washed with water and asaturated aqueous sodium chloride solution and then dried with magnesiumsulfate. After natural filtration, the filtrate was concentrated and theobtained solid was recrystallized with chloroform and hexane, therebyobtaining 562 mg of objective 9-phenyl-10-(4-bromophenyl)anthracene as alight-brown solid with a yield of 45%.

[Step 2]

A method for synthesizing9-(4-{N-[4-(9-carbazolyl)phenyl]-N-phenylamino}phenyl)-10-phenylanthracene(abbr.: YGAPA) is explained. Synthetic Scheme (f-5) of YGAPA is shownbelow.

409 mg (1.0 mmol) of 9-phenyl-10-(4-bromophenyl)anthracene, 339 mg (1.0mmol) of YGA obtained in Step 1 of Example 7, 6 mg (0.01 mmol) ofbis(dibenzylideneacetone)palladium(0), 500 mg (5.2 mol) of sodiumtert-butoxide, 0.1 mL of tri(tert-butyl)phosphine (a 10 wt % hexanesolution), and 10 mL of toluene were collected, mixed, and stirred for 4hours at 80° C. After the reaction, the solution was washed with waterand a water layer was extracted with toluene. The water layer was washedwith a saturated aqueous sodium chloride solution in conjunction withthe organic layer and dried with magnesium sulfate. After naturalfiltration, the filtrate was concentrated and the obtained oilysubstance was purified by silica gel column chromatography(hexane:toluene=7:3). The obtained solid was recrystallized withdichloromethane and hexane, thereby obtaining 534 mg of objective YGAPAas a yellow powder solid with a yield of 81%. By measuring this compoundby a nuclear magnetic resonance method (NMR), the compound wasidentified as9-(4-{N-[4-(9-carbazolyl)phenyl]-N-phenylamino}phenyl)-10-phenylanthracene(abbr.: YGAPA). ¹H NMR charts of YGAPA are shown in FIGS. 34A and 34B.

Synthetic Example of CzPA

Hereinafter, a method for synthesizing9-[4-(N-carbazolyl)]phenyl-10-phenylanthracene (abbr.: CzPA) representedby Structural Formula (202) is explained.

Synthetic Scheme (h-1) of 9-[4-(N-carbazolyl)]phenyl-10-phenylanthracene(abbr.: CzPA) is shown below.

1.3 g (3.2 mmol) of 9-phenyl-10-(4-bromophenyl)anthracene, 578 mg (3.5mmol) of carbazole, 50 mg (0.017 mmol) ofbis(dibenzylideneacetone)palladium(0), 1.0 mg (0.010 mmol) oftert-butoxysodium, 0.1 mL of tri(tert-butyl)phosphine (a 10 wt % hexanesolution), and 30 mL of toluene were collected, mixed, and refluxed for10 hours while heating at 110° C. After the reaction, the solution waswashed with water, and a water layer was extracted with toluene andwashed with a saturated aqueous sodium chloride solution in conjunctionwith the organic layer. Then, the organic layer was dried with magnesiumsulfate. The mixture was naturally filtered and the filtrate wasconcentrated. The obtained oily substance was purified by silica gelcolumn chromatography (hexane:toluene=7:3). The obtained solid wasrecrystallized with dichloromethane and hexane, thereby obtaining 1.5 gof objective 9-[4-(N-carbazolyl)]phenyl-10-phenylanthracene (abbr.:CzPA) with a yield of 93%.

NMR data of the obtained CzPA are shown below. ¹H NMR (300 MHz, CDCl₃);δ=8.22 (d,J=7.8 Hz, 2H), 7.86-7.82 (m, 3H), 7.61-7.36 (m, 20H). Inaddition, ¹H NMR charts are shown in FIGS. 35A and 35B.

Note that 5.50 g of the obtained CzPA was purified by sublimation for 20hours under conditions at 270° C., with an argon flow (at a flow rate of3.0 mL/min), and under a pressure of 6.7 Pa, thereby recovering 3.98 gwith a recovery rate of 72%.

Synthetic Example of BSPB

Hereinafter, a method for synthesizingN,N′-bis(spiro-9,9′-bifluorene-2-yl)-N,N′-diphenylbenzidine (abbr.:BSPB) represented by Structural Formula (203) is explained.

[Step 1]

First, a method for synthesizing 2-bromo-spiro-9,9′-bifluorene isexplained. Synthetic Scheme (j-1) of 2-bromo-spiro-9,9′-bifluorene isshown below.

1.26 g (0.052 mol) of magnesium was put into a 100-mL three-neck flaskand stirred while heating for 30 minutes and activated with a systemevacuated to vacuum. After cooling to a room temperature, the system wasput in a nitrogen flow. Then, 5 mL of diethyl ether and a few drops ofdibromoethane were added, and 11.65 g (0.050 mol) of 2-bromobiphenyldissolved in 15 mL of diethyl ether was gradually dropped. Afterdropping, the mixture was refluxed for 3 hours, thereby producing aGrignard reagent. 11.7 g (0.045 mol) of 2-bromofluorenone and 40 mL ofdiethyl ether were put into a 200-mL three-neck flask. The synthesizedGrignard reagent was gradually dropped into this reaction solution, andthe mixture was refluxed for 2 hours after the completion of droppingand stirred for about 12 hours at a room temperature. After thereaction, the reaction solution was washed with a saturated aqueousammonia chloride solution twice. A water layer was extracted with ethylacetate twice and washed with a saturated aqueous sodium chloridesolution in conjunction with an organic layer. After drying withmagnesium sulfate, the organic layer was filtered by suction andconcentrated, thereby obtaining 18.76 g of9-(2-biphenylyl)-2-bromo-9-fluorenol as a solid with a yield of 90%.

Next, 18.76 g (0.045 mol) of the synthesized9-(2-biphenylyl)-2-bromo-9-fluorenol and 100 mL of glacial acetic acidwere put into a 200-mL three-neck flask. A few drops of concentratedhydrochloric acid were added and the mixture was refluxed for 2 hours.After the reaction, the precipitate was recovered by suction filtration,and washed by filtration with a saturated aqueous sodium hydrogencarbonate solution and water. The obtained brown solid wasrecrystallized with ethanol, thereby obtaining 10.24 g of a light-brownpowder solid with a yield of 57%. This light-brown powder solid wasidentified as 2-bromo-spiro-9,9′-bifluorene by a proton nuclear magneticresonance method (¹H NMR).

¹H NMR of this compound is shown below. ¹H NMR (300 MHz, CDCl₃);δ=7.86-7.79 (m, 3H), 7.70 (d, 1H, J=8.4 Hz), 7.47-7.50 (m, 1H),7.41-7.34 (m, 3H), 7.12 (t, 3H, J=7.7 Hz), 6.85 (d, 1H, J=2.1 Hz),6.74-6.70 (m, 3H).

[Step 2]

Next, a method for synthesizingN,N′-bis(spiro-9,9′-bifluorene-2-yl)-N,N′-diphenylbenzidine (abbr.:BSPB) is explained. Synthetic Scheme (j-2) of BSPB is shown below.

1.00 g (0.0030 mol) of N,N′-diphenylbenzidine, 2.49 g (0.0062 mol) of2-bromo-spiro-9,9′-bifluorene synthesized in Step 1, 170 mg (0.30 mmol)of bis(dibenzylideneacetone)palladium(0), and 1.08 g (0.011 mol) oftert-butoxysodium were put into a 100-mL three-neck flask, and thesystem was put in a nitrogen flow. Then, 20 mL of anhydrous toluene and0.6 mL of tri(tert-butyl)phosphine (a 10 wt % hexane solution) wereadded, and the mixture was stirred for 6 hours at 80° C. After thereaction, the reaction solution was cooled to a room temperature andthen water was added. The precipitated solid was recovered by suctionfiltration and washed with dichloromethane. The obtained white solid waspurified by alumina column chromatography (chloroform) andrecrystallized with dichloromethane, thereby obtaining 2.66 g of whitepowder solid with a yield of 93%.

The following result was obtained by analyzing the obtained white powdersolid by a proton nuclear magnetic resonance method (¹H NMR), and theobtained white powder solid could be identified asN,N′-bis(spiro-9,9′-bifluorene-2-yl)-N,N′-diphenylbenzidine (abbr.:BSPB). In addition, a ¹H NMR chart is shown in FIG. 36. ¹H NMR (300 MHz,DMSO-d₆); δ=7.93-7.89 (m, 8H), 7.39-7.33 (m, 10H), 7.19-7.14 (m, 8H),7.09-6.96 (m, 6H), 6.89-6.84 (m, 8H), 6.69 (d, 4H, J=7.5 Hz), 6.54 (d,2H, J=7.8 Hz), 6.25 (d, 2H, J=2.4 Hz).

Note that 4.74 g of the obtained compound was purified by sublimationunder conditions of 14 Pa and 350° C. for 24 hours, thereby recovering3.49 g with a recovery rate of 74%.

This application is based on Japanese Patent Application serial no.2005-302853 filed in Japan Patent Office on Oct. 18, 2005, the contentsof which are hereby incorporated by reference.

1. An aromatic amine compound represented by General Formula (1),

wherein each of Ar¹ to Ar³ represents an aryl group having 6 to 12carbon atoms or a heteroaromatic group having 4 to 9 carbon atoms; eachof R¹ to R³ represents an alkyl group having 1 to 4 carbon atoms or anaryl group having 6 to 25 carbon atoms; each of R¹¹ to R¹³ represents ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an arylgroup having 6 to 25 carbon atoms; and each of R²¹ to R²³ represents ahydrogen atom, a methyl group, or a methoxy group.
 2. An aromatic aminecompound represented by General Formula (2),

wherein Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; R¹ represents an alkylgroup having 1 to 4 carbon atoms or an aryl group having 6 to 25 carbonatoms; R¹¹ represents a hydrogen atom, an alkyl group having 1 to 4carbon atoms, or an aryl group having 6 to 25 carbon atoms; and each ofR²¹ to R²³ represents a hydrogen atom, a methyl group, or a methoxygroup.
 3. An aromatic amine compound represented by General Formula (3),

wherein Ar¹ represents an aryl group having 6 to 12 carbon atoms or aheteroaromatic group having 4 to 9 carbon atoms; R¹ represents an alkylgroup having 1 to 4 carbon atoms or an aryl group having 6 to 25 carbonatoms; and R¹¹ represents a hydrogen atom, an alkyl group having 1 to 4carbon atoms, or an aryl group having 6 to 25 carbon atoms.
 4. Anaromatic amine compound represented by Structural Formula (21).